Do PC power supplies really put out the power they claim? - Page 1
Forum section: electronics / general

author: wilfred
author_rank: Super Contributor
timestamp: October 25, 2013, 11:48:07 pm
content: .

author: Psi
author_rank: Super Contributor
timestamp: October 25, 2013, 11:51:31 pm
content: Cheap ones (<$80) = not a chance, some switch off before 30% of their rated currentMid-range ones ($80-150) = maybe 50-70% of rated current and 100% peak currentExpensive ones ($150-500) = Pretty much 100% of rated current, or very close to it.All of them share a wattage over multiple rails. You can't draw max current out of all rails simultaneously, even on the expensive ones.It usually says this on the label, etc, 5V @ 30A, 12V @ 40A and.. 480W max between 5V and 12V rails etc..

author: edavid
author_rank: Super Contributor
timestamp: October 26, 2013, 12:05:11 am
content: If you look around, you can find reviews where they actually test this. For example:http://www.tomshardware.com/reviews/power-supply-review-80-plus-bronze,3568.htmlOne of the supplies they tested there is the Antec HCG-400, which according to the tests works fine at 100% load. I bought one for $11 last year, so I think it counts as a cheap PS.

author: Psi
author_rank: Super Contributor
timestamp: October 26, 2013, 12:12:13 am
content: lol yeah, i never would have expected that.

author: george graves
author_rank: Super Contributor
timestamp: October 26, 2013, 12:20:29 am
content: www.pcper.comseems to do some decent testing. You might find this interesting.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: October 26, 2013, 12:26:06 am
content: The answer to this question is most reputable ones do (though even some of those are a bit optimistic).My favorite site for PC PSU reviews ishttp://www.jonnyguru.comYou get in depth load testing, voltage stability testing, efficiency, transient testing, ripple tests, tear downs, etc. He uses a couple of SunMoon digital loads as well as some other stuff to really get in depth on testing the ripple, load etc. He also uses a "hot box" to test how well it performs at its highest rated temp.

author: wraper
author_rank: Unknown
timestamp: October 26, 2013, 12:51:06 am
content: Quote from: Psi on October 25, 2013, 11:51:31 pmNot so bad, they can be divided to such categories but prices will be lower. That also depends how much watts they promise for the price. If $50 psu is 350W it is true in most cases, however no way you get real 500w for the such price. Rails are virtual most of the time, just wires connected to single point. Should be considered as how much power you can connect to certain wire. That's for sure you can't pull all written current because total current x voltage of them will be bigger than total power of the PSU. Only high power PSU's, like >800W usually have real separate rails (because there are 2 transformers).

author: Phaedrus
author_rank: Frequent Contributor
timestamp: October 26, 2013, 01:05:31 am
content: Some do, some don't. Most reputable brands will do their rated wattage fine.I'll be brutally honest: until fairly recently, CoolerMaster was not a very reputable brand. We have sold, and still sell, some power supplies with inflated wattage ratings. But as PSU Product Manager in the US, I'm trying to change that. We've EOL'd, or are in the process of EOLing, all of our overrated power supplies. We've got a new vendor for high-end parts (SeaSonic), and a new low-end product to replace the ones we're phasing out, which I have personally tested and it can do its rated wattage. The efficiency sucks and the capacitors are poor, but it can do its rated wattage.Many brands though, like Raidmax, Coolmax, Allied, Diablotek, Athena, Ultra, and many others, including hosts of "ebay" brands, cannot do what the label claims. Typical overrating values are 20-40%, but can go as high as 80-100%. Once a 1000W was tested as being a 550W in disguise.Brands that generally (>95% of the time) do their rated wattage are (the new) CoolerMaster, Antec, Rosewill, Corsair, FSP, SeaSonic, Enermax / Lepa, Zippy, Kingwin, SuperFlower, XFX, etc.Dave, if you like I could send you a review sample of our V850 or V1000 power supplies. They're great little units, 87-91% efficient between 20% and 100% load, voltage regulation around 1.2% on the +12V rail, ripple under 30mV on the +12V and under 15mV on the +5V and +3.3V*. Uses an advanced LLC Resonant Full Bridge topology based on a CM6902 controller, with +5V and +3.3V rails buck regulated from the +12V. Very nice unit, ODM is SeaSonic. We sell 'em at a bargain price too. Interested?* Based on ATX testing spec, which requires a 10uF and a 0.1uF cap parallel to the probe, and o-scope set to 20MHz.

author: Fsck
author_rank: Super Contributor
timestamp: October 26, 2013, 03:43:34 am
content: @ Phaedrus : no offense, but using brands to determine if a power supply is any good is horrible in the consumer pc world especially since most brands just rebrand other platforms and often use different ODMs and different platforms depending on the exact model. Seasonic and Superflower are the only two OEMs of note though Superflower is more Eurasia than NA but they're becoming more popular in NA.You're better off sticking to OEM/ODMs. Seasonic, Flextronics, Superflower are the typical top notch consumer world. CWT is of variable quality depending on the platform, they tend to only be good for performance/price . Delta and Zippy are the server kings (sometimes they do consumer platforms and their consumer variants again depend on the platform).For power requirements, many people attempt to have idle sit at 10-25% of a power supply's maximum rated power and full load at 50-75% to maximize lifetime and efficiency. I have a Seasonic M12 850W, computer idles at 120-150W and full load at 400-450W. my NAS has a CWT made, Corsair branded 750W. it idles at 80-100W.Triple SLI can pull 1000W easy from the graphics cards alone, especially if overclocking heavily/extremely

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 26, 2013, 05:00:46 am
content: Another trick that helps a lot with reliability/lifetime is to increase the airflow at load. Easy way to do it (without voiding the warranty) is to pressurize the case with a nice Delta. Or you can spend extra for a PSU designed for server use.

author: Psi
author_rank: Super Contributor
timestamp: October 26, 2013, 06:55:17 am
content: Quote from: NiHaoMike on October 26, 2013, 05:00:46 amand wear earmuffs when using the PC

author: amyk
author_rank: Super Contributor
timestamp: October 26, 2013, 11:19:10 am
content: Quote from: wilfred on October 25, 2013, 11:48:07 pmThis is very true. The vast majority* of PCs out there are going to have a PSU that is overrated, but it doesn't matter because even at full load the total consumption is <200W; all the cheap ones tend to top out around there, for this reason.One experience with a vendor in Shenzhen's SEG market (going through a translator so maybe some of the meaning was lost):Me: is this PSU really 600W?Her: it says 600WMe: can it output 600W continuously?Her: no, do you need that?Me: then what is the real output power?Her: 200WMe: why do you say it has 600W then?Her: 600W is just the label for show, we can customise the label for additional 5 yuan only.Me:...ok. (walks away with translator)* PCs that are going to be used by the "average user" - a low-end dual, maybe quad core at the most, integrated graphics, one HDD, and nothing else. It'll probably spend the bulk of its life idling at <50W too, being used occasionally for Facebook and such.

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 26, 2013, 01:41:46 pm
content: Quote from: Psi on October 26, 2013, 06:55:17 amThe variable speed Deltas (which have Cindy Wu FOC drive) aren't noisy most of the time.

author: echen1024
author_rank: Super Contributor
timestamp: October 26, 2013, 02:34:24 pm
content: I use an Intel quad core i5 2500k at 4.2GHz, with a dual SLI NVidia 660, and my computer draws <50W idle with Virtu. When things get cranked up though, it goes upwards of 500W

author: niflheimer
author_rank: Contributor
timestamp: October 28, 2013, 12:01:00 pm
content: I'm currently using a Sirtec ( Hi-Power ) Element 550W . The first thing I did once I got it maybe four years ago was to put it on a DC load - It passed my test without any problem , though it was a bit hot after half an hour with a 540W load ( the max load I had at my workplace ).I usually recommend mid to top end Corsairs , some Antecs , Seasonics if I had the chance to open them up and Sirtecs . I've actually seen a 550W Sirtec driving a dual 480GTX setup with a vastly overclocked 8150 - was drawing close to 700W from the wall . It's been more than two years since then and it's still kicking . On the other hand I had a 500W Sirtec release its magic smoke in 24h after buying it so YMMV .

author: madires
author_rank: Super Contributor
timestamp: October 28, 2013, 02:19:40 pm
content: Lovely topic :-) I always tried to buy good PSUs but failed sometimes. For example Tagan. Nice specs, tests with good results in local computer magazines and a price point indicating that the PSU isn't cheap. After the first failed I opened it and wasn't suprised about I found, cluttered PCB and so on. So I decommissioned them all! A more recent Enermax 80+ (tidy PCB) promised better efficiency but running 24x7 it crashed from time to time and required a coffee brake for power cycling. Currently I'm using Superflower 80+Gold and it seems to be a very nice PSU, it's also less expensive than a similar Enermax. The power usage of my little server went from 80W (Tagan) down to 60W (Superflower). 20W less per year saves me about €40 (yes, power is that expensive here) and after 2 years the new PSU will have paid for itself :-)

author: ConKbot
author_rank: Super Contributor
timestamp: October 28, 2013, 05:07:52 pm
content: I'd suggest not buying a power supply if its not reviewed well onhttp://www.hardwaresecrets.com/page/powernot only do they tear down each power supply to the component level and comment on the quality of parts used. They do a 100% load test with voltage ripple measurements, efficiency, power factor, the works. I'd be impressed to see someone have a more though testing/review available.