switching-PSUs: why can't you usually exceed the 50% of declared power? - Page 1
Forum section: electronics / projects

author: 0db
author_rank: Frequent Contributor
timestamp: May 23, 2020, 08:43:06 pm
content: The Superflower Leadex is a great series of Switching-Mode PSUs, and if you buy a 650 Watt unit, you can be sure the unit will serve you up to 650 Watt without dropping voltage, or increasing the voltage ripple.But let's talk about cheaper PSUs. I have recently seen a lot of 500 Watt units where you cannot exceed th 50% of the declared power, thereore if you buy a 500 Watt, it will serve you only up to 250 Watt, and beyound it might get damaged.What I cannot understand is why. Which are the technical reasons for this? And what one should look into the circuit to have some enlightenments about the quality of the product concerning its behavior under load?Thanks

author: wraper
author_rank: Unknown
timestamp: May 23, 2020, 08:50:54 pm
content: Unless you buy cheapest garbage usually you can run them at 100% or nearly 100% load for prolonged time.QuoteReally, is it that hard to figure it out? It's cheaper to build lower quality PSU with fake ratings. More power/ higher efficiency = more expensive to produce.

author: 0db
author_rank: Frequent Contributor
timestamp: May 23, 2020, 09:04:53 pm
content: Quote from: wraper on May 23, 2020, 08:50:54 pmI'd like to know details: is it for capacitors? if so, which is the difference between "good" capacitors and "bad" capacitors? And is there any table around telling which are good ones (vendor/models/etc)?Is it for the transformer? Filters? Protection chip? Oscillators? What does make a PSU a "bad" PSU?It's too easy to say "oh, because it's cheap". Cheap means all and nothing.

author: ejeffrey
author_rank: Super Contributor
timestamp: May 23, 2020, 09:15:45 pm
content: Not enough capacitance, not enough core material, not enough copper, not enough silicon, and not enough cooling. Too low temperature ratings and too much ripple current. Even if the PSU is designed correctly, if parts are substituted at manufacturer time that can cause any of the above issues.There are lots of ways to cheap out, not just one.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 23, 2020, 09:34:22 pm
content: Quote from: 0db on May 23, 2020, 08:43:06 pmWhere did you see this? Do you have an example of an ATX that can't operate over 50%? Are you sure you're not talking about efficiency dropping above 50% or something like that?

author: wraper
author_rank: Unknown
timestamp: May 23, 2020, 09:34:37 pm
content: Quote from: 0db on May 23, 2020, 09:04:53 pmIt's everything, including smaller transformer.

author: richard.cs
author_rank: Super Contributor
timestamp: May 23, 2020, 09:42:11 pm
content: Think of it like taking a 250 W PSU, removing any overload protection, then slapping a 500 W sticker on it and selling it as 500 W. Fundamentally all the power components are undersized for 500 W, there isn't usually just one component where they cheaped-out.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 23, 2020, 09:50:50 pm
content: Quote from: richard.cs on May 23, 2020, 09:42:11 pmDo you know of any examples of this, or are you just speculating?

author: 0db
author_rank: Frequent Contributor
timestamp: May 23, 2020, 10:05:16 pm
content: Quote from: engrguy42 on May 23, 2020, 09:34:22 pmI bought a couple of AEROCOOL VX PLUS 550W just to make a few tests.They litteraly exploded at 300Watt of load. And there was no PFC inside.

author: 0db
author_rank: Frequent Contributor
timestamp: May 23, 2020, 10:09:08 pm
content: CORSAIR VS 650W inside a PC at work. Same bitter end.It worked only up to 450 Watt, then it presented overvoltage at its lines, and the motherboard died.

author: tunk
author_rank: Super Contributor
timestamp: May 23, 2020, 10:12:59 pm
content: Here's a few others:https://www.jonnyguru.com/blog/2012/12/03/death-of-a-gutless-wonder-iii-the-labors-of-hercules/http://www.jonnyguru.com/blog/2013/03/11/death-of-a-gutless-wonder-iv-aces-low/https://www.jonnyguru.com/blog/2014/05/12/death-of-a-gutless-wonder-v-uncool-to-the-max/

author: chriva
author_rank: Regular Contributor
timestamp: May 23, 2020, 10:14:38 pm
content: Where did you load it and how?If you don't have proper equipment to measure actual load, you can't really say "it blew at this and that wattage".Just because a GPU states it'll only draw 150 Watts doesn't mean that is actual peak power. They can easily push almost twice that with a slight overclock.Processors are pretty much as bad. Design power is far under their boost power draw

author: rsjsouza
author_rank: Super Contributor
timestamp: May 23, 2020, 10:21:58 pm
content: Quote from: 0db on May 23, 2020, 10:05:16 pmOthers already mentioned what could be cheaper. Think about your own experience with the "explosion" and imagine the manufacturer used a cheaper 15A MOSFET trying to carry 25A or 30A on the 3.3 or 5V lines, or used a 30A MOSFET but reduced the size of the heatsink. Both scenarios are quite possible for a catastrophic scenario but rarely go alone: the use of lower quality PCBs with smaller current capacity, bad soldering job due to low salaries, use of components removed from other products, etc.I have seen all these in a plethora of power supplies sold in the marketplace - the worst offenders were in the periphery markets such as Brasil and Argentina (the ones I know better), where the supplies were sold as "500W (300W real)"

author: 0db
author_rank: Frequent Contributor
timestamp: May 23, 2020, 10:26:07 pm
content: Quote from: chriva on May 23, 2020, 10:14:38 pmI attached several bulbs in parallel to simulate the load. I started with a few bulbs to simulate 100Watt, then I added more bulbs to simulate 200Watt, 300Watt, and finally 500Watt. During the test I observed the ripple with an oscilloscope.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 23, 2020, 10:30:10 pm
content: Hold on here...some alarm bells are going off...Some basic questions:- Are these new or used units?- What tests did you do?The reason I ask is that decent ATX power supplies are required to provide some basic protection. They generally have supervisor circuits which monitor output current and voltage and shut down the switching MOSFETS quickly when out of range. They also have fuses. I've done a significant amount of testing on a decent ATX supply, and the supervisor circuit worked great. I overloaded it multiple times with a huge rheostat and it shut down instantly.Now, I would be fairly certain that a Corsair unit would have these protections. So something seems fishy here. "The motherboard died??".If you pay for used or extremely cheap power supplies you shouldn't be asking the question. You get what you pay for.If you're paying for a decent, ATX power supply, I suggest you take a look at the protection circuits it's supposed to have (look at the ATX spec) and see what supervisor circuit is inside and what it's supposed to do.I'm not saying nothing bad can ever happen, I'm saying a string of failures sounds more like user error (or cheap/used junk) than bad units.

author: 0db
author_rank: Frequent Contributor
timestamp: May 23, 2020, 10:34:34 pm
content: Quote from: engrguy42 on May 23, 2020, 10:30:10 pmI bought them from Amazon, declared "new".

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 23, 2020, 10:57:22 pm
content: For some perspective, here's something very similar to the supervisor circuit on my Dell ATX power supply. And this is from a Dell desktop that's like 5-10 years old. As you can see it's monitoring current AND voltage on 5 outputs (3.3, 5, & 12v). It checks overvoltage, overcurrent, and undervoltage.And it has protection on the input (fuse, MOV's, PFC, etc.).So blowing up really isn't a reasonable likelihood, nor is destroying the motherboard. Hence my skepticism.Of course that won't stop the anti-ATX fanboys from jumping to the assumption that these ATX supplies are just crap, but anyway...

author: 0db
author_rank: Frequent Contributor
timestamp: May 23, 2020, 10:59:57 pm
content: Quote from: engrguy42 on May 23, 2020, 10:30:10 pmOverCurrent Protection?umm, my old Cooler Master MASTERWATT 550W had a slow OCP protection at 600 Watt.The PSU didn't shutdown immediately, only after 1 sec later with a VDrop of 0.8V at 12V.Paid 50 euro for it, not exactly "cheap", it went back to Amazon.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 23, 2020, 11:08:10 pm
content: Quote from: 0db on May 23, 2020, 10:59:57 pmI suggest you take a look at the Intel ATX power supply design guide. It's extremely informational if you want to understand ATX supplies. Here's a snip of the allowable voltage regulation. Note it says +12V output can get down to 11.4 which is slightly higher than what you measured. I'm not sure how you measured and how accurate you were, but it seems reasonable. And if you were acutally measuring the -12VDC, it says it can get down to -10.8

author: 0db
author_rank: Frequent Contributor
timestamp: May 23, 2020, 11:19:53 pm
content: +12V - 0.8V = 11.2V < 11.4V ---> not acceptable! I initially measured it on the oscilloscope, then I repeated the experiment with a multimeter of 3 digits in parallel. Same result.Anyway, OVC meansover current protection. If the PSU has a limit of 550Watt, and you try to sink out 600Watt, it should immediately shutdown. Not after 1 sec, but rather the soonest possible!

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 23, 2020, 11:38:01 pm
content: Again, look at the Intel ATX design guide. It tells you exactly what the requirements are. I'm not sure why you feel 1 second is too long. Is that what the spec says? If the spec doesn't say the operating time then there's not much you can do.As far as your supply dipping to 11.2 rather than 11.4...why is that important? Yeah, it's outside the spec, but does that really matter?

author: 0db
author_rank: Frequent Contributor
timestamp: May 23, 2020, 11:48:03 pm
content: Quote from: engrguy42 on May 23, 2020, 11:38:01 pmBecause in 1 sec it was enough to overheat, and it started making bad smell. Parts were for sure stressed.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 23, 2020, 11:49:38 pm
content: BTW, here's what it says about overcurrent protection. No more than 240VA on each rail, greater than that causes a trip. Test that at a minimum rate of 10A/second. So taking 1 second to trip seems pretty reasonable.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 23, 2020, 11:52:05 pm
content: Quote from: 0db on May 23, 2020, 11:48:03 pmCome on, did you actually measure the temperatures? Were they high enough to damage anything? You're really worried about it taking 1 second to trip?

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 12:01:27 am
content: Hold on...the OCP section I posted was from an older version. Here's the 2018 version

author: 0db
author_rank: Frequent Contributor
timestamp: May 24, 2020, 01:23:55 am
content: Quote from: engrguy42 on May 23, 2020, 11:52:05 pmI am more worried about the AEROCOOL VX PLUS 550W, because it didn't even shutdown; at 250Watt of load it made smoke until it exploded, and at this point the lifesaver in my appartment interrupted the energy, but before it happened, the measured p-p ripple was over 300mV on the 12V line, and this for sure can damage things like harddrives and VRMs.The Superflower Leadex costs 120 euro. As soon as I tried to connect a 650 Watt load it immediately cut of the power, and during all the tests the p-p ripple over the 12V line was a flat line, always about 30mV!- Fast OVP!- flat line p-p ripple!- fair rating on the the labelIt's a true 650Watt PSU!Now you have two examples. One very bad PSU, one very good PSU.

author: wizard69
author_rank: Super Contributor
timestamp: May 24, 2020, 01:47:02 am
content: Scam artist and ethics problems from manufactures in China. If you are going to buy hardware form China you need to know the ins and outs of the industry and who the reliable manufactures are. Obviously there are a lot of good manufactures in China but there are also many that are nothing but scam artist out to make a quick buck. The big problem for the rest of us is separating the ethical manufactures from the dealers in Junk.There is also no legal structure in China that effectively polices the manufactures there. There has to be a massive public outrage for the Chinese government to take action. Look up the problems they recently had with vaccines for Children.Quote from: 0db on May 23, 2020, 08:43:06 pm

author: tautech
author_rank: Super Contributor
timestamp: May 24, 2020, 01:55:10 am
content: You cannot assess a PSU with light bulb loads OR its capability if loading only one rail !Each output can only be loaded to its rated output and several output loads may be necessary to reach its full rated output in watts.....but specs may be only in watts consumption NOT total output.Further, tungsten bulbs have high initial current draw until the filament reaches operating temp where its resistance is muchlowerhigher than when cold. This inrush current could send the SMPS into shutdown.All ^^^ traps for the unwary !Edit to correct brain fart.

author: rsjsouza
author_rank: Super Contributor
timestamp: May 24, 2020, 10:15:03 am
content: Quote from: tautech on May 24, 2020, 01:55:10 am100% agree, but an exploding power supply is totally unacceptable. So, the lightbulbs are not necessarily useles as you can still separate the wheat from the chaff.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 10:36:39 am
content: I know folks just LOVE to make sweeping generalizations and dismissals about stuff, but usually they are incorrect.Anyway, as I said, decent power supplies don't blow up, for many reasons. Look at the ATX requirements. And realize those are MINIMUMS. Decent manufacturers add to those to make sure they don't provide crap and thereby ruin their reputations.Nobody here knows why your power supplies failed. Nor can we since we don't know the internals of the power supplies or what you did to test them and so on. If you want to believe that all power supplies that aren't the Superflower are junk, and can't be loaded past 50%, go right ahead. If you want to believe that if it was manufactured in China it's probably junk, go ahead. You'll get a lot of fanboys here agreeing. And you'll certainly get a lot of anti-ATX fanboys agreeing with anything that anyone says that's negative towards ATX supplies. You'll even get people saying they're bad because a bug can crawl in and zap it.But if you're interested in the truth, do some research. Look inside the failed power supplies and see what happened. And see what the supervisor circuit is, and what it's designed for.Without that it's all just vague speculation about stuff nobody understands.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 24, 2020, 11:09:16 am
content: Quote from: tautech on May 24, 2020, 01:55:10 amyup on 12V rail, i can see its less than half the 450W PSU rating, ie 18A, so its only half the story. btw, last time i bought Gigabyte brand ATX PSUs for my PC, decent price. both died prematurely in less than a year, the second one only for few weeks, they only have nice nylon wires grouping sheathing, cute big fans and quality like exterior black paint, but functionally abysmal. then i thought what the heck, let me just buy the cheap $20 one (TronMonxter from Tatu) its surprised me when they can survive for like 4-6 years. the second one i just dismantled not because it blows up dead, its still working, its just the wiring near connectors becomes stiffen and broken in few pins and places making my PC shut off from time to time for sometime now. now i cant stand it so my PC is on a new cheapo PSU again only starts working for few days now, no more intermittent shut off no more corrupted hibernated data on power up. i keep reusing the nice nylon sheathing power connectors that i stripped from Gigabyte PSU to get more connectors for my many HDD/SDD/DVD etc because the cheap one has too few on it, so the dead Gigabyte is not entirely useless. i will keep 1 or 2 PSU unit in stock bought every year or 2, coz i know the working one will sometime failed unexpectedly, so keeping in stock will not leave me in the dark for a day or 2 while finding a shop that can supply me a PSU. some of them are even dirt cheap like $10 i can buy 2 or 3 units in one receipt if i want to, but i dont want to occupy much of my storage space there are many more items to store, not just ATX PSUs. so on rare occasion, this is where you buy cheaper to get better product..

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 11:22:17 am
content: Quote from: Mechatrommer on May 24, 2020, 11:09:16 amParticular PSU has 42A/504W rating on 12V rail out of 550W total. Any modern half-decent ATX PSU has at least 80-90% of total power rating on 12V rail.

author: PKTKS
author_rank: Super Contributor
timestamp: May 24, 2020, 11:27:22 am
content: Quote from: Mechatrommer on May 24, 2020, 11:09:16 amTRUE.The ATX sticker ratings are meaningless - they just sum the rails.Making tests on a single rail is also meaningless - different supervisorssample the output in different ways.Cheap ATX up to 500W **VERY CAREFUL CHOSEN** can deliverup to 300W on a well balanced load.Apart this you have a bad setup.I do have a lot of those cheapos - they work fine if proper balancedAerocool VX series can deliver 350W just fine in well balanced systemsHalf bridge cheap designs they all use cheap components and requirea proper and careful load balance for proper operation.IT IS NOT LIKE: "HEY 500W in a single 12V rail ... exploded?"obvious it will explodePaul

author: strawberry
author_rank: Super Contributor
timestamp: May 24, 2020, 11:27:30 am
content: What can be found in cheap psu: They use BJT even today. Input filter cap size less than ~1uF per watt. Poorly designed control loop (oscilation, voltage overshoot !) and controller. Stadard instead of low ESR. Poor quality enemaled copper wire. Heat and loss is not a thing (POWER). Rock and sand do not improve encapsolated psu heat disipation. Poor conductivity silicone rubber thermal pads.500w psu have to disipate ~100w@80% of heat.

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 11:27:56 am
content: Photo of this trash

author: PKTKS
author_rank: Super Contributor
timestamp: May 24, 2020, 11:35:38 am
content: Quote from: strawberry on May 24, 2020, 11:27:30 amThere is nothing wrong using BJTs in FULL BRIDGE and HALF BRIDGEsMY BENCH 1200W (60V@20A) is a HALF BRIDGE uc38xx current modebased one - and does the job just fine.Under 600W ATX half bridges are cheaperthey also DON'T REQUIRE TRUE SINE WAVE INVERTERSYOU CAN COMBINE 2 to have affordable high power in casethey cost less and do the jobdrawback is that you have a lot of bad ones and you needto choose very carefully you also need to balance the systemAnd cheap systems (like those used SOHO or POS) justdo not require a 600W PFC with true sine inverter to operate.Below 350W real power a cheap ATX with much more cheapnon -sinus inverter will more than half the budget.REASON to use them? COST.Paul

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 11:52:05 am
content: Quote from: PKTKS on May 24, 2020, 11:35:38 amAgain you promoting and defending trash PSUs. In bench PSU efficiency it is no so critical, we often use even linear PSUs. What's wrong with BJT is guaranteed subpar efficiency / high heat dissipation. And when talking about ATX PSUs in particular, that nowadays you will find them only in trash models.EDIT: and when you find them in driving transformer in bench PSU, usually it's either because PSU is old or model is produced for a long time. Or simply because it's a cheap trash too.

author: PKTKS
author_rank: Super Contributor
timestamp: May 24, 2020, 12:01:25 pm
content: Quote from: wraper on May 24, 2020, 11:52:05 amYes, I have literally dozens of them without problems.I use them literally for decades including several smallPSUs for bench work - all half-bridge design - all BJT basedI use HIGH COST PFC based ones in HIGH END PC GAMERswhere the cost literally explodes any budget.A TRUE SINE WAVE INVERTER au pair with that ATX is also requiredand considering benefits - IMHO they do not worth the money.For the record: I AM NOT "PROMOTING" garbage.Stop saying such shitI am putting simple facts. Where they are not neededthose expensive solutions are expensive crapMy bench uses 5 HALF BRIDGE BJT based PSUs for decadesdaily based - nothing wrong with that.SOHO and POS give a shit if 70% 80% or 90% ratingsthey care about monthly TOC (ownership cost)Me too. I give a shit if 80% plus gold or shit.I care about total monthly costPaul

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 12:12:24 pm
content: Quote from: PKTKS on May 24, 2020, 12:01:25 pmYeah, and garbage you advocate for has higher cost of ownership in any country where electricity price is not dirt cheap.QuoteThen why everyone laughed at you in the last thread where you praised PSU which internally is basically the same as trash discussed in this thread?

author: PKTKS
author_rank: Super Contributor
timestamp: May 24, 2020, 12:18:56 pm
content: Quote from: blueskull on May 24, 2020, 12:15:22 pmMy opinion about those small cheap patented supervisoradapters is unprintable.I have a box of failed ones - supervisors (OBxx and TOPxx) are mostlyRCC (very poor ratings) designs..patented and almost dispensable garbage.Last month I just ditch 7 failed IOT of those.They just do not worth the hassle...Paul

author: PKTKS
author_rank: Super Contributor
timestamp: May 24, 2020, 12:21:05 pm
content: Quote from: wraper on May 24, 2020, 12:12:24 pmSuit yourself - the money you put in your hardware is all yours.There is nothing to laugh on my simple well put facts.Just the cost which includes repair and probably replacingthose advocated "better" ones.Being there several times - they are just as bad and more expensive.Paul

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 12:37:52 pm
content: FWIW, it's a myth that higher efficiency power supplies save you a lot of money on your electric bills. Do the math.In the US the average cost of electricity is about 13 cents per kWH. In Brazil it's like 14 cents (US). If you calculate the difference in kWH ACTUALLY used with a 90% efficiency power supply versus an 80% power supply it amounts to maybe a few US $$ per year. A bit like the cost savings by running around your house and turning off a 50 watt light bulb when it's not being used.Unless you run your computer at maximum load 24 hours a day, 365 days a year....

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 24, 2020, 12:45:51 pm
content: Quote from: wraper on May 24, 2020, 11:27:56 amthe topology is not much better than cheapo one. they can make nice fan and stickers, enclosure paint, nylon sheath and any spec list they want and put a sound price to it... the way they cut corner on surge protection/PFC stage is just similar to a $10 unit, maybe thats where they outsourced/get their supply from. just for fun, i dig back the $40+ damaged Gigabyte PSU, 1st pic, no cut corner on surge protection, plastic insulation on both sides, look at that nice heatsinks, it can be reused for other project thats why i keep them (i keep more damaged PSU for parts than the working one). but even that beauty, its a PoweRock my ass only worked for about less than a year iirc. 2nd picture is the $20 TronMonxter, no surge protection (cut corner), less 50W power, but worked for 3-4 years. go figure... cheaper is better! ps: both pic below shows better/beefier main transformer than your shown trash.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 12:53:09 pm
content: Quote from: blueskull on May 24, 2020, 12:40:21 pmThat's up to you...as long as you realize the facts, and how it's no different than, say, leaving your air conditioner on a few extra minutes a few times a year when you don't really need it. And so on.Power supply efficiency, for most, amounts to maybe a few $$ per year. If that matters, then fine. As long as people are aware, and not just handwaving on stuff they don't really understand.

author: coppice
author_rank: Super Contributor
timestamp: May 24, 2020, 12:53:24 pm
content: As well as all the issues of cheaper designs being stripped to the bone to sell at crazy low prices, there are also issues of how the load is spread among the output rails. You can only get up to the rated maximum with any PC supply if you load each of the outputs by the right amount.Older supplies focussed a lot of their capacity on the lower voltage rails, and not enough on the 12V outputs to suit modern PCs. Modern supplies have limited capacity on the lower voltage outputs, and most of the capacity is on the 12V outputs. The supplies for most rack mount servers only output 12V these days, and PCs will probably go his way. However, supplies they often have multiple 12V output sections, and you need the load to be balanced across those sections to get close to the rated capacity.

author: PKTKS
author_rank: Super Contributor
timestamp: May 24, 2020, 12:55:28 pm
content: Quote from: engrguy42 on May 24, 2020, 12:37:52 pmThanks... for the clever comment.ABSOLUTE TRUE.This is a total wrong argument. The savings on the billpromoted by such "ratings" 80% 90% gold plus shit are garbage.Those PSUs are targeted to high end PCs where you usehungry power GPUs which waste awesome 700W of true powerplus ownership costs.SOHO and POS are well below 300W and the cost focusis more on hardware wearing out soon than the mains billTheir air conditioner is ORDERS OF MAGNITUDE above...on the mains bill and their pile of PCs are a real problem.So saving more than double the cost on EACH OF THEM..is a very good argument with their managers.Paul

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 12:58:00 pm
content: Quote from: engrguy42 on May 24, 2020, 12:53:09 pmIf computer works 8 hours a day, when comparing decent and cheapo PSU, power consumption difference over about 1-3 years will cover price difference and in some places even buy you additional good quality PSU.

author: coppice
author_rank: Super Contributor
timestamp: May 24, 2020, 01:05:37 pm
content: Quote from: engrguy42 on May 24, 2020, 12:37:52 pmFor most people moving from an 80% efficient supply to a 90% efficient supply in their PC will not save much in electric bills, because their PC is only working hard for a small percentage of the time. However, for server, telecoms and other high power applications running flat out 24 hours a day every extra percent of efficiency brings a big enough reduction in power bills to justify significantly higher complexity in their power supplies. Try looking at the materials used to promote multi-kilowatt supplies in the 95% to 97% efficiency area. Its all about cost breakdowns over the life of the equipment.For consumers a shift from 80% efficiency to 90% efficiency is not useless. Halving the supply's heat output helps compact machines to run cool with a very quiet fan.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 01:06:54 pm
content: Quote from: wraper on May 24, 2020, 12:58:00 pmAgain, you're free to believe whatever you want, but if you actually look at the numbers for your ACTUAL usage you may find out that's not the case.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 24, 2020, 01:08:13 pm
content: please also remember a PC is not the only thing in a (full family) house. TV, hifi, wifi router etc use SMPS. and sometime 3-5 PC/laptop in the house. promoting for extra 10% efficiency and making a habit to turn off appliances when not in use can buy you a good toy within a year.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 24, 2020, 01:08:49 pm
content: Quote from: tautech on May 24, 2020, 01:55:10 amSpeaking of traps, I think you meant the resistance is much higher than when cold.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 01:10:33 pm
content: Quote from: coppice on May 24, 2020, 01:05:37 pmIf you look hard enough you can always find an exception to anything. Of course, commercial and industrial usage is ENTIRELY different. We're talking average users, who don't know any better. Commercial and industrial users know exactly what it's costing them.And it's easy to make vague generalities like "lower heat is better", but in practical terms it's likely irrelevant in terms of effects on actual service life, etc.

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 01:14:58 pm
content: Quote from: PKTKS on May 24, 2020, 12:55:28 pmTotal bullshit. Even if computer consumes only 100W, 10% consumption difference is a big deal. And estimation in my previous post is based on such figure for office use. If there is high-end GPU and frequent gaming involved it becomes even more noticeable and more expensive PSU may pay off in less than a year.

author: Monkeh
author_rank: Super Contributor
timestamp: May 24, 2020, 01:16:24 pm
content: Quote from: engrguy42 on May 24, 2020, 01:10:33 pmHowever the difference in component quality between the low efficiency garbage certain people are promoting and a decently made and efficient supplyisrelevant in terms of service life.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 01:20:29 pm
content: Quote from: wraper on May 24, 2020, 01:14:58 pmAgain, do you have ACTUAL numbers to support this, or is it just vague generalizations based on personal belief?

author: mikerj
author_rank: Super Contributor
timestamp: May 24, 2020, 01:23:38 pm
content: Quote from: wraper on May 24, 2020, 01:14:58 pmAll depends. A single computer at home used maybe a couple of hour a day or so and the savings will be barely noticeable. A whole office full of PCs running 24/7 and the savings start to look a bit more compelling.

author: Monkeh
author_rank: Super Contributor
timestamp: May 24, 2020, 01:26:27 pm
content: I had a machine with an ~80% efficient (at this load) supply which ran 24/7/365, at about 85W at the wall. If I'd had a.. less than stellar supply in it such as those suggested, call it 95W. That amounts to something around £10-20 a year (prices vary wildly, apparently the current average is 14.37p/kWh, or £12.59 a year). That's not that different to the cost difference between a cheap trash supply (about £15-20) and a current 80+Gold supply (about £45). That machine was in said use for four or five years.Meanwhile, I spent £20 and replaced it with something using 20W at the wall.. paid for itself in months.

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 01:30:00 pm
content: Quote from: engrguy42 on May 24, 2020, 01:20:29 pmSay ((15W (efficiency difference) * 8h * 261 days + 3W * 24h (standby PSU efficiency) * 365 d) * $0.20 kWH = $11.5

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 01:52:13 pm
content: Quote from: wraper on May 24, 2020, 01:30:00 pmSo you're running your computer at full power for 8 hrs/day, 365 days/year?

author: coppice
author_rank: Super Contributor
timestamp: May 24, 2020, 01:56:40 pm
content: Quote from: engrguy42 on May 24, 2020, 01:52:13 pmHaven't you seen how gamers live?

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 01:58:02 pm
content: Quote from: engrguy42 on May 24, 2020, 01:52:13 pmCheck the numbers again, there are 261 days. 365 for standby part. If it was my computer, difference would be much higher since I run it about 12-14 hours a day, and especially if I ran it "at full power" since it's high end PC with high-end GPU.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 02:06:32 pm
content: My suggestion for those who really want to understand computer power supply and GPU power usage...Get a cheap kWH monitoring device (like a KillAWatt), and plug your computer into it. It will tell you the ACTUAL kWH usage of your entire computer (including GPU) over time. You can then calculate the difference if it had a different efficiency power supply, and calculate a more realistic value of cost savings.GPU's and other computer components don't use a fixed amount of power during the day, nor do they operated at maximum ratings all day. It varies. And in some/many cases they never reach their rated power specification, depending on the software they're running.You may be surprised that the cost savings you thought you were getting just aren't there.

author: coppice
author_rank: Super Contributor
timestamp: May 24, 2020, 02:11:45 pm
content: Quote from: engrguy42 on May 24, 2020, 02:06:32 pmI'd recommend any serious engineer to get a KillAWatt or two, and monitor some of the things around their home. Anyone competent knows the approximate power consumption of most of the stuff around the house, but usage patterns determine the total energy consumed. Those patterns are not always obvious until you start making some measurements. It can be quite revealing.

author: PKTKS
author_rank: Super Contributor
timestamp: May 24, 2020, 02:15:18 pm
content: Quote from: engrguy42 on May 24, 2020, 02:06:32 pmVery true indeed.Add to the list of costs a REQUIRED TRUE SINE INVERTERfor those setups using PFC based sensitive loads.A couple of months a guy called me asking my opinionabout someone trying to sell him a "PC" above the barrel...with multi-core i9 power latest gen GPU and awesome 1000W PSUWhich included a TRUE SINE INVERTER NoBreak of 2KWJust to run MS word on a desktop dozen times a day.The folk argument is that MS Win GUI now requires a GPUfor proper display office and an i9 multi-core CPU withliquid cooling is required to handle ANTI VIRUS stuffOf course the gain margin of the folk was considerable as wellI gave him my opinion which is absolute unprintable here...Paul

author: Monkeh
author_rank: Super Contributor
timestamp: May 24, 2020, 02:58:08 pm
content: Quote from: engrguy42 on May 24, 2020, 02:06:32 pmThe figures I measured were at idle of a configured system. Consumption simply will not have been lower at any time. I'm sorry this doesn't support your argument, but that's the problem with biases.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 24, 2020, 03:05:21 pm
content: Quote from: coppice on May 24, 2020, 02:11:45 pmI'd recommendUni-T UT210Ecan be used to design SMPS as well..

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 04:28:46 pm
content: Quote from: Monkeh on May 24, 2020, 02:58:08 pmI wasn't responding to you, and honestly I'm not sure what point you were trying to make. And my only argument is to suggest people look at the facts by actually measuring rather than supposing. Honestly I couldn't care less what anyone here chooses to do.

author: Monkeh
author_rank: Super Contributor
timestamp: May 24, 2020, 04:40:39 pm
content: Quote from: PKTKS on May 24, 2020, 02:15:18 pmAnd yet I achieve uptimes measured in years with no REQUIRED TRUE SINE INVERTER in sight. No INVERTER at all, actually. Or anything else in all-caps you might want to mention..

author: coppice
author_rank: Super Contributor
timestamp: May 24, 2020, 04:45:46 pm
content: Quote from: Monkeh on May 24, 2020, 04:40:39 pmMany countries are not familiar with a public power supply more reliable than the bulk of UPS solutions.

author: Siwastaja
author_rank: Super Contributor
timestamp: May 24, 2020, 04:50:32 pm
content: Why do we have this inrush of 11-year-old* gaming kids spewing 500 posts worth of arrogant bullshit in no time, on such fine engineering forum?*) Physical or mental, doesn't matterIs it the new general computing section?

author: nfmax
author_rank: Super Contributor
timestamp: May 24, 2020, 04:51:08 pm
content: Quote from: coppice on May 24, 2020, 04:45:46 pmThough even there, it may not be TRUE SINE mains anyway:https://www.eevblog.com/forum/projects/show-us-your-mains-waveform!/

author: Monkeh
author_rank: Super Contributor
timestamp: May 24, 2020, 04:53:46 pm
content: Quote from: coppice on May 24, 2020, 04:45:46 pmIndeed. But that does not mean everyone using a computer globally requires a UPS.

author: wizard69
author_rank: Super Contributor
timestamp: May 24, 2020, 06:11:09 pm
content: Quote from: 0db on May 23, 2020, 09:04:53 pmWhy do you want to know, cheap or scam hardware is what it is. A bad supply can be the result of many things from one substandard component to the whole thing being built to one standard with a label slapped on it indicating another capability. In some cases it is a simple as that, a label gets slapped on a device that does not meet the devices designed specs.QuoteCheap means everything. It can mean cutting corners. It can mean out right lies about a products capability. Or it can simply mean that the cheapest parts possible got embedded in the PSU. This really isn't hard to understand.

author: wizard69
author_rank: Super Contributor
timestamp: May 24, 2020, 06:46:38 pm
content: Quote from: Monkeh on May 24, 2020, 04:53:46 pmMore importantly people can buy laptops with batteries included if power is a real issue. Cheaper than a UPS. Marginal utilities can be a problem anywhere and as such laptops are a good way to deal with that. Yes I realize that a laptop does not replace a workstation performance wise but that is another issue.To pull the discussion back on track a bit laptop power adapters are not the most reliable things either. Again if varies from manufacture to manufacture but one can see awfully high failure rates in these adapters.

author: Monkeh
author_rank: Super Contributor
timestamp: May 24, 2020, 07:27:49 pm
content: Quote from: wizard69 on May 24, 2020, 06:46:38 pmConsequence of the primary design compromises: Size and cost. That and being left on carpets, getting blankets tossed on them, and so forth.IME the ones used on cheap tat like MSI and Acer aren't stellar, the ones supplied with the business grade machines tend to be tougher.

author: bdunham7
author_rank: Super Contributor
timestamp: May 24, 2020, 08:06:24 pm
content: Quote from: engrguy42 on May 24, 2020, 12:37:52 pmPerhaps some people buy high efficiency PSUs for reasons other than saving a lot of money on their electric bill.

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 08:10:00 pm
content: Quote from: bdunham7 on May 24, 2020, 08:06:24 pmThe thing is in the end you don't save anything by buying trash power supply. If you don't save, what's the reason to buy trash?

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 08:12:59 pm
content: Quote from: Siwastaja on May 24, 2020, 04:50:32 pmI especially like the ones who crank their GPU's to max while sitting on their butts playing video games for 14 hours a day, blowing away gazillions of kWH in energy costs and waste all year, and then claim to care about a higher efficiency power supply to save $2 a year in energy costs. Or the ones who leave the 4,000 watt central air conditioner on an extra hour or two, thereby erasing much of their yearly cost savings.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 09:15:14 pm
content: Quote from: bdunham7 on May 24, 2020, 08:06:24 pmAnd those reasons would be?

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 09:16:11 pm
content: Quote from: engrguy42 on May 24, 2020, 09:15:14 pmNot buying junk?

author: 0db
author_rank: Frequent Contributor
timestamp: May 24, 2020, 10:37:35 pm
content: Buy a Corsair power supply.Even Mr.LTT looks lost.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 11:32:05 pm
content: Love how he caters to the 4 minute experts.Actually it's kinda sad.

author: chriva
author_rank: Regular Contributor
timestamp: May 24, 2020, 11:33:30 pm
content: LTT is not the correct place to get that type of information.Granted, I have a hard time not trusting Corsair since I expect them to do proper research before arranging a deal with OEM's (they don't produce their own supplies)Many of their supplies are built by SeaSonic and CWT.If you buy the cheapest shit they have to offer, I do suspect you get what you pay for tho...I've stuck to their supplies with 5 year warranties and none have failed. Oldest one is 13 years old now and I've only replaced the fan since it started to make some noise but other than that, it's A OK.Do I trust their supplies that are out of warranty? -_NO_. Should you trust any supply that is that old no matter which brand? _NO_(!)To the actual point: Don't buy the cheapest shit you can find. It doesn't matter which manufacturer it is.

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 11:34:34 pm
content: Quote from: engrguy42 on May 24, 2020, 11:32:05 pmWhat's sad? It's video on Corsair youtube channel. What did you expect?

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 11:37:21 pm
content: Quote from: chriva on May 24, 2020, 11:33:30 pmIt's not LTT. As of information, it's good enough for general public. When Corsair gets mentioned every time, what did you expect in their own video, duh.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 11:38:35 pm
content: Quote from: wraper on May 24, 2020, 11:34:34 pmI was talking about him and his channel, in general. As well as all the other tech youtubers who have given up and cater to those who have the attention span of a mosquito and only want to be entertained.But I get it, you're just looking for mud to throw.

author: wraper
author_rank: Unknown
timestamp: May 24, 2020, 11:43:02 pm
content: Quote from: engrguy42 on May 24, 2020, 11:38:35 pmYou watch infomercial on youtube channel of company that sells PSUs. Then make some dumb comment about it. WTF do you expect from infomercial?

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 24, 2020, 11:46:40 pm
content: Quote from: wraper on May 24, 2020, 11:43:02 pmBoy, somebody disagrees with you in some tech discussion and you get all cranky and start hatin' on peopleRelax.

author: bdunham7
author_rank: Super Contributor
timestamp: May 25, 2020, 12:58:08 am
content: Quote from: engrguy42 on May 24, 2020, 09:15:14 pmLet me put it another way. Some people may end up buying high efficiency power supplies because they want a particular power supply for other reasons, such as overall quality or features, and in the process end up with a high efficiency PSU. I can only speak definitively for myself, so the two times I can remember offhand that I went for a high-efficiency unit, what I was really after was quiet and cool, for HTPC applications. In one, I used a 600W semi-fanless (no fan until half power) unit with very high efficiency (don't remember the number) in an application that maxes out a bit over 200W. It also lightens the load a bit on the UPS I suppose, but that's a minor consideration. I don't care about the power bill.I think most high-quality units today will also be relatively high efficiency, although perhaps not the other way around. Can you think of a counter-example, a high-quality low-efficiency PSU? I can't.

author: bdunham7
author_rank: Super Contributor
timestamp: May 25, 2020, 03:20:25 am
content: Quote from: 0db on May 23, 2020, 08:43:06 pmAccording to many internet teardown reviews, there are a lot of PSUs with shoddy build quality, even name brands. But that doesn't explain why they blow up, if indeed they do. I did some GPU BitCoin mining for a few years and of course doing that you need to do it as cheaply as possible. I had multiple rigs that used about 400W and I started with some cheapo 500W PSUs and they all failed in days or weeks. I didn't disassemble them, so IDK what killed them, but they didn't catch on fire or fry anything, they just stopped working. The helpful Microcenter guy suggested some generic 'PC Power and Cooling' 750W units and those worked for years. I still have one or two. The only two differences I'm certain of between the two PSU types are that the 500W units didn't have enough hold-up time to reliably allow my UPS to kick in, and that the larger units were significantly more efficient (as measured with a KillaWatt device) although I don't have a number offhand. It was something like 20 or 30W less at the wall.My best guess is that cheap no-name brands will have the cheapest, smallest parts and will be optimistically rated. I suppose most people don't push the limits and if their overall warranty rate isn't too high things are good enough.

author: 0db
author_rank: Frequent Contributor
timestamp: May 25, 2020, 09:59:27 am
content: Quote from: chriva on May 24, 2020, 11:33:30 pmBefore buying I checked all the "customers reviews" on Amazon and on websites, including the eBay forum for consumers: 90% incorrect to what I personally measured.I measured something like 15 units, of which 11 returned to Amazon.The last three tests of yesterdaysharkoon silentstorm coolzero 650 watt (120 euro)seasonic prime gold 750 watt (130 euro)asus rog thor 850 watt (240 euro)The asus rog thor is really impressive! I will return it just because it's too expensive, but it's a truly great piece of technology

author: 0db
author_rank: Frequent Contributor
timestamp: May 25, 2020, 10:00:03 am
content: All tests concernthe ripple under load (all rails have resistive loads)the operating voltages range (are ATX ranges respected?)the protection against overcurrent (does it turn off immediately?)Next weekend, I will go ahead with tests on cheap PSUs in the range 50-60 euro.I can open the metal frame to have a look, but I am not able to say a word about internal components. I don't have any scientific criteria to test the "visual" quality.If you show me the pic of a very bad PSU, and the pic of a very good PSU, I am not able to distinguish them without putting them on the testbench, but this kind of "visual" test is very useful when you happen to buy "frameless PSUs", just the naked circuit without any metal, from China.My next micro-business.

author: engrguy42
author_rank: Frequent Contributor
timestamp: May 25, 2020, 10:30:46 am
content: Quote from: 0db on May 25, 2020, 09:59:27 amSo you bought 15 power supplies, ran them thru some tests including overloading them, performing tests on units you admit you don't understand, as well as the ATX specification which you don't understand (and apparently weren't aware of), and when they fail/blow up you return 11 of them?

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: May 25, 2020, 10:36:57 am
content: It's also important noting that you can't just draw all that current from one supply. If a supply says 600W, it usually means x W on the 12V CPU, y W on the 12V PCIe-additional cables, z W on the 5V/3.3V rails, etc. And in the end, x+y+z will end up adding to 600W.A 600W supply can not provide 600W on its 3.3V line. If it could, it would come with chunky cables.

author: madires
author_rank: Super Contributor
timestamp: May 25, 2020, 01:03:05 pm
content: Quote from: 0db on May 23, 2020, 08:43:06 pmIt's the same story as why the cheap 1A USB charger for one buck (or 2 incl. shipping) delivers just 0.5A before the voltage breaks down.

author: wraper
author_rank: Unknown
timestamp: May 25, 2020, 01:51:28 pm
content: Quote from: TheUnnamedNewbie on May 25, 2020, 10:36:57 amNot true for most and particularly any decent power supply. 12V rail is often rated close to the total power rating. Other rails have lower ratings but if you count power ratings of separate rails, usually you would come up with something like 700-750W for 600W PSU. Thus separate rail power ratings overlap within total power rating. But total output power of all rails of course should not exceed total power rating. If you see x+y+z = 600W for 600W PSU, that's a dead giveaway you are looking at piece of crap.

author: Mechatrommer
author_rank: Super Contributor
timestamp: May 25, 2020, 02:04:11 pm
content: Quote from: wraper on May 25, 2020, 01:51:28 pmsays who?Quote from: wraper on May 25, 2020, 01:51:28 pmand again, says who? most likely its just "your" definition of a "crap". its like saying whoever says 1+1+1=3 is a crap math, 1+1+1 should be 4 or 5.

author: PKTKS
author_rank: Super Contributor
timestamp: May 25, 2020, 02:09:05 pm
content: 2cents of this jambo..Some folks seems rather spoiled with obtainingFULL MAXIMUM POWER from the advertisedfantasy label of those PSUs.I never go past 70% rated single rail ...Well balanced setup usually are fineIf you think those "value" series like Aerocool VX or KCASare garbage.. YOU WILL FREAK OUT WITH THESE ONES..I use them a lot on the bench and small POS (under 150W power)Usually with a widely available S-360 SMPSATX DC-DC module converters on the flyusing ANDERSON connections (above 20A)Paul

author: tunk
author_rank: Super Contributor
timestamp: May 25, 2020, 02:11:18 pm
content: I also wondered about that, so I checked these two PSUs:Cooler Master 400W (MPX-4001-ACABW-EU) where the specs adds up to 542W.Corsair CV450 450W (CP-9020209-EU) where the specs adds up to 617W.

author: wraper
author_rank: Unknown
timestamp: May 25, 2020, 02:16:01 pm
content: Quote from: Mechatrommer on May 25, 2020, 02:04:11 pmSays GOOGLE ATX PSU label. Find PSUs where rail power ratings added together equal to total power rating, then note on what kind PSUs you can see that. Based on that you don't need to be genius to guess that power rating is inflated.

author: 0db
author_rank: Frequent Contributor
timestamp: May 25, 2020, 05:29:39 pm
content: Quote from: engrguy42 on May 25, 2020, 10:30:46 amYou love doing antagonism, don't you?Sorry, I am not interested.

author: 0db
author_rank: Frequent Contributor
timestamp: May 25, 2020, 05:44:30 pm
content: Quote from: tunk on May 25, 2020, 02:11:18 pmInteresting. I haven't tested them yet, and these two are in the "cheap" rangeDid you also test the ripple and the voltage range?

author: 0db
author_rank: Frequent Contributor
timestamp: May 25, 2020, 05:51:25 pm
content: I have just bought a power meter, it's not professional, but I hope to measure the "Power Factor Correction" (PFC) somehow.Learning alot new things

author: tunk
author_rank: Super Contributor
timestamp: May 25, 2020, 06:06:34 pm
content: I haven't tested them, I just looked up the specs and added it up.