What is the motivation of intel to want PSUs that are 12V only? - Page 1
Forum section: electronics / general

author: epigramx
author_rank: Regular Contributor
timestamp: March 05, 2020, 10:04:44 am
content: https://www.intel.com/content/dam/www/public/us/en/documents/guides/single-rail-power-supply-platform-atx12vo-design-guide.pdfThe introduction claims that it is high time for PSUs to become more efficient.But why would they want to make other circuits less efficient?

author: Rerouter
author_rank: Super Contributor
timestamp: March 05, 2020, 10:13:43 am
content: Almost all high power computer switching supplies are built around using the 12V rail, with RAM and onboard peripherals barely pulling anything from the 5V rail, and due to the whole molex/sata thing, even 3.3V rails are getting less popular, as its not hard to locally down convert from 5V.the RAM and other mid current loads on a motherboard are not hard to shift back to the 12V rail, in fact a number of overclocking boards already do this to save costs on unique parts when you need high current power stages.When you pulling say 40A @ 12V, loosing 2-3W in switching losses for the lower power low voltage rails may be much better if you gain back 30W on the initial conversion of that high current load.

author: Zero999
author_rank: Super Contributor
timestamp: March 05, 2020, 10:29:57 am
content: Because losses in cables, at very low voltages are high. Assuming everything else is equal, halving the voltage, results in four times the losses in cables. This is because P = I2R, reducing the voltage requires double the current, for the same power and 22= 4.Modern switched mode power supplies can be very efficient, so it make more sense to distribute a higher voltage and perform the voltage regulation, as close to the load, as possible. This is done with mains electricity, which is transmitted over long distances, at high voltages >100kV and stepped down to lower and lower voltages near the the load: 10kV is common around towns and cities, with 120V to 400V only traveling a few hundred metres.

author: epigramx
author_rank: Regular Contributor
timestamp: March 05, 2020, 10:31:24 am
content: Quote from: Rerouter on March 05, 2020, 10:13:43 amSo you're implying they're going to favor very high power PCs with this and consider low power desktops a minority.

author: bd139
author_rank: Super Contributor
timestamp: March 05, 2020, 11:13:55 am
content: I was getting all excited when I saw this mostly from the vain hope that they'd get rid of Molex connectors. But nopeAs for the multiple voltages, this is a legacy hang back going back as far as the 1980s. Even latest normal ATX spec has -12V still. That needs to die.If they introduce single voltage that means smaller, simpler, more reliable power supplies, easier to manage power supply efficiency etc. And every device can ship with its own slave switching converters to get whatever voltages it needs out. The biggest consumer in my PC is currently yanking 116.3A @ 1.475V which is quite frankly a shit load of current so I'd rather have that being converter right next to where it is being used which is exactly what's happening now.Also if everything is 12V, consider laptops etc. If all peripherals standardise on that we're getting smaller desktop PCs too which would be mostly cooling rather than fat bundles of snakes in a gigantic box.

author: G7PSK
author_rank: Super Contributor
timestamp: March 05, 2020, 11:25:02 am
content: I can't see the problem, laptops have only one voltage input and do every thing onboard as do many of the ultra small computers, may also be easier for power factor correction on the mains.

author: epigramx
author_rank: Regular Contributor
timestamp: March 05, 2020, 12:08:36 pm
content: Quote from: Zero999 on March 05, 2020, 10:29:57 amThat's a good point, because the alternative is more efficient because there are usually lower losses in PCB connections.That raises the question though why not go 15V or 20V or 24V since they are relatively human safe.

author: Circlotron
author_rank: Super Contributor
timestamp: March 05, 2020, 12:19:23 pm
content: Quote from: epigramx on March 05, 2020, 12:08:36 pmMy guess is because you would use a synchronous buck regulator for local conversion to the lower voltage, and when you start going to say 24V input to the reg you need a pair of mosfets with say 30V rating and consequently a higher RDSon figure than a lower voltage mosfet, hence higher conduction losses. Don't forget you have to switch the same current that goes out of the reg but at the voltage that goes in. Maybe 12V is the sweet spot?

author: tunk
author_rank: Super Contributor
timestamp: March 05, 2020, 12:29:03 pm
content: The cynic in me says it's because the total cost is lower.A positive side effect may be higher efficiency.

author: langwadt
author_rank: Super Contributor
timestamp: March 05, 2020, 12:34:13 pm
content: Quote from: Circlotron on March 05, 2020, 12:19:23 pm12v is a nice compromise for gate drive

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 05, 2020, 01:10:41 pm
content: The adoption of USB-C that supports adjustable voltage is phasing out a lot of 5V rail load.

author: madires
author_rank: Super Contributor
timestamp: March 05, 2020, 01:17:48 pm
content: Many high efficiency ATX PSUs have just a 12V secondary anyway, i.e. the other voltages are created by DC/DC converters fed by the 12V rail. This design improves the overall efficiency. No need to mess around with regulating multiple secondaries. Moving the DC/DC converters to the mainboard will help a little bit more with the efficiency.

author: tszaboo
author_rank: Super Contributor
timestamp: March 05, 2020, 03:15:28 pm
content: In the server world, this switch was made a long time ago . It resulted a much smaller power supply. An DC-DC stepdown is now probably cheaper than the wire and the connector. But I really hope they dont stop here, and finally design a successor for the ATX (not BTX) because this one is getting outdated. Without the 5.25" stuff if possible please. And power and data through 1 cable for drives please.

author: tooki
author_rank: Super Contributor
timestamp: March 05, 2020, 04:12:30 pm
content: Quote from: epigramx on March 05, 2020, 10:31:24 amNo, it's not "favoring" them. High-power PCs simply represent the larger challenge; low-power ones will still benefit.

author: tooki
author_rank: Super Contributor
timestamp: March 05, 2020, 04:14:03 pm
content: Quote from: NANDBlog on March 05, 2020, 03:15:28 pmAnd also, doesn't 12V only also make it super easy and efficient to provide battery backup using 12V SLA batteries, instead of complex and inefficient UPSs? I recall reading years ago about Google rolling its own motherboards using 12V only, with a connector for a 12V battery right on the mobo.

author: OwO
author_rank: Super Contributor
timestamp: March 05, 2020, 04:19:06 pm
content: 12V is still way too low. A 500W system would draw 42A, which is difficult to transport and requires huge connectors with many pins. 48V is more reasonable; the motherboard can then step it down to 12V and then to the individual voltages. DC-DC conversion stages are never a problem; I use single rail supply even for small modules (e.g. FPGA board + daughterboards), and always generate all rails locally.EDIT: pretty sure google uses 48V at the server level and something like 400V DC at the rack level.Personally I would go with 70V. It's the highest I can still comfortably touch and at this level the higher the better. The DC-DC converter on the motherboard doesn't have to be transformerless.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 05, 2020, 04:35:50 pm
content: Quote from: OwO on March 05, 2020, 04:19:06 pm12V is part of the legacy I think, but there's another reason IMO. The idea of down-converting voltages more locally is generally a good one. But 12V is likely close to the sweet spot for the following reason: step-down converter ICs that operate with higher input voltages than this are just going to be much more expensive, as this gets into the "high-voltage" territory for current CMOS processes. 48V or over would make local step-down converting much more expensive. You could say that you can always chain them to overcome this, but then you have a chain of efficiencies which would make efficiency for the low voltages (which currently draw the most current on computer motherboards) pretty poor. Just a thought.

author: Gregg
author_rank: Super Contributor
timestamp: March 05, 2020, 07:15:55 pm
content: Single 12VDC would certainly make sense for a UPS type system; no inverter needed.

author: Red Squirrel
author_rank: Super Contributor
timestamp: March 05, 2020, 07:40:38 pm
content: Would be cool if they made it 13.5v actually, would make power backup simpler, just needed a battery set to float voltage. Currently, PCs have lot of power rails so doing a straight DC type backup would be too complex. 3.3v, 5v, 12v, -12v... I feel I'm missing one. Is there a -5v?Really a 48v/54v standard would be cool. That's how telecom gear works.

author: ve7xen
author_rank: Super Contributor
timestamp: March 05, 2020, 07:57:25 pm
content: Quote from: CJay on March 05, 2020, 05:00:58 pm-48VDC is even more legacy than the 12V rail in ATX. It goes back to telco central office standards and their lead-acid battery plants, probably predates home computers entirely. Still common in telecom to have -48VDC as the main power distribution, so most gear you might find in a telco facility (networking, servers, etc.) will have a PSU option for that. It does make a lot of sense from a high reliability point of view, it's a simple design and easy to scale, but it also probably wouldn't be the choice if you were in a completely green field today.

author: mariush
author_rank: Super Contributor
timestamp: March 05, 2020, 08:42:07 pm
content: My guess is that this is requested a lot by OEM manufacturers like HP and Dell who want to reduce the number of wires and save a few pennies this way and get less complaints about proprietary / custom connectors on their power supplies.HP is known for using custom connectors in their workstation systems for example, Dell also has some power supplies with custom connectors.It's an OK move but it's sad that Intel didn't have the guts to go further and work with power supply and motherboard manufacturers to innovate further.Seems like they just stuck to 12v standby and 12v to power everything.I would like to see a new revision of the standard to introduce 20v (-10% .. 5%) (to allow possibility of powering a system from DC In barrel jack using 18.5v adapters common in laptops), while keeping 12v for backwards compatibility.20v is standardized in USB, so having 20v and 12v would make it possible to use USB connectors to power a monitor for example, or fancier external storage.It shouldn't be very hard for the psu to include some kind of microcontroller or something with a usb 1.0 or 2.0 connection to the system, allowing the system to communicate with the psu and enumerate capabilities ...For example i'm 12v only, i'm 12v and 20v, i'm 20v only (motherboard could have this tiny chip by the DC In connector and detect 12v or 18.5v..20v and pretend it's a psu with 12v only or 20v only ... useful for small systems with an APU that consume 40-60w max... power them from a 90w laptop adapter or a 200w atx psu)...psu could also say current on each voltage, total wattage, indicate if the 12v is derived from 20v using dc-dc converters..motherboard can query and get number of fans, fan rpm, may even be able to tell psu to adjust fan rpm (but psu would have the final say as in motherboard can't override psu's safeties ... if psu controller needs to spin fan at 50% to keep cool, user would not be able to force fan to shut down)maybe support rgb if the power supply has leds inside...With just two output voltages it could be possible to have a current shunt on each 12v or each 20v pair of wires ... or worst case per 2x4 connector (eps, pci-e 6/8 pin etc)...Some would argue 5v should also stay as an option , as that could allow future very low power laptops and tablets to be powered completely from a 10-15w 5v laptop adapter but nah, lots of usb chargers have option to go up to 12v or higher and dc-dc converters are tinier and tinier and more efficient.

author: Circlotron
author_rank: Super Contributor
timestamp: March 05, 2020, 08:59:31 pm
content: Quote from: Circlotron on March 05, 2020, 12:19:23 pmFurther to this, to maintain the same peak to peak ripple current in the buck reg inductor, you need proportionally greater inductance as the input voltage goes up. More copper means greater losses.

author: tszaboo
author_rank: Super Contributor
timestamp: March 05, 2020, 10:41:24 pm
content: Quote from: OwO on March 05, 2020, 04:19:06 pmNah. There are only 28 buck converters from TI above 70V, with max current of 3A. There are over 240 with max voltage between 14 and 24V, with max current of 40A. And you dont end up with large ripple voltage and current, and big capacitors and inductors. 12V is a good compromise.

author: ajb
author_rank: Super Contributor
timestamp: March 05, 2020, 10:51:35 pm
content: Quote from: tunk on March 05, 2020, 12:29:03 pmThe total cost is lower *because* it's more efficient, though, no cynicism required. At least within the context of a desktop PC, what's the disadvantage of moving to a single power rail and PoL converters wherever needed?

author: David Hess
author_rank: Super Contributor
timestamp: March 06, 2020, 12:44:41 am
content: Quote from: SiliconWizard on March 05, 2020, 04:35:50 pmThe ratio of input to output voltage for a transformer-less converter is a factor. 48 volts to 1 volt yields about a 2% duty cycle which makes things difficult, although not impossible, so it is usually better, and more efficient, to invert 48 volts to a lower voltage and then use a buck converter for the lowest voltage supplies. Vicor actually sells inverters and regulated converters to do this.

author: coppice
author_rank: Super Contributor
timestamp: March 06, 2020, 12:58:29 am
content: Quote from: OwO on March 05, 2020, 04:19:06 pmNobody is going to standardise a mother board voltage that high. It would classify the board as dangerous, and require shielding to restrict a user's access to it. One of the reasons PCs have done so well is the flexibility that came from having all the high voltage stuff packaged in a small shielded box, so the ordinary user can have free and easy access to anything inside the PC's case.The EU's Low Voltage Directive is probably the benchmark for the highest voltage you will see leaving the fully encased power supply of any computer in the foreseeable future.

author: langwadt
author_rank: Super Contributor
timestamp: March 06, 2020, 01:01:43 am
content: Quote from: coppice on March 06, 2020, 12:58:29 amI always thought the limit was 50V, but it seems the EU limit is 50V AC and 75V DC

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 06, 2020, 01:12:55 am
content: Quote from: Red Squirrel on March 05, 2020, 07:40:38 pmLead acid is old technology that's declining as lithium becomes cheaper. The existing 12V standard matches up with a 3S pack pretty well.

author: langwadt
author_rank: Super Contributor
timestamp: March 06, 2020, 01:31:07 am
content: Quote from: NiHaoMike on March 06, 2020, 01:12:55 am3S is a bit on the low side and 4S a bit on the high side, but both is in the ball park

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 06, 2020, 01:54:58 am
content: 4S is too much for devices that expect a well regulated 12V. But it does work nicely for "12V" devices designed with unregulated wall warts in mind, e.g. a lot of home network hardware.

author: DBecker
author_rank: Frequent Contributor
timestamp: March 06, 2020, 02:55:35 am
content: The opportunity for higher efficiency is using a single power rail. With a single power rail the supply doesn't have to handle the extreme of power drawn mainly on 3.3V (typical a few years ago), or primarily on 12V (e.g. a GTX Titan Z GPU on a system that otherwise is using 20W).The typical power-hungry chip is running at 0.9-1.2V. VRM efficiency drops like a rock with a buck conversion ratio of much over 10 (under 10% duty cycle), so 12V is at the upper end of the range.50V is the 'safe low voltage' limit in some regions, so a European regulation allowing 75VDC (presumably the Low Voltage Directive LVD 2014/35/EU) isn't a design target for global products. 48V has been used in telecom for about a century, and thus was the natural choice for a DC server supply when that started being a requirement two decades ago.

author: amyk
author_rank: Super Contributor
timestamp: March 06, 2020, 04:31:46 am
content: Two words: planned obolescence.Instead of putting the highly-stressed power semiconductors in a separate easily replaceable module, build them into the more expensive and difficult to repair motherboard so as to limit its lifetime and repairability.

author: OwO
author_rank: Super Contributor
timestamp: March 06, 2020, 04:35:49 am
content: Quote from: NANDBlog on March 05, 2020, 10:41:24 pmThat's why I saidThe DC-DC converter on the motherboard doesn't have to be transformerless.You do not use a buck converter to go from 70V to 12V, you use a transformer and have plenty of topologies to pick from - isolated Cuk, forward, flyback, etc etc. Discrete synchronous rectifiers (ideal diodes) exist, and plus at this power level you could afford a CPLD controlled FET switch on the output side rather than diodes.70V is what I would go with if I were designing a system for my own use and can disregard regulations, I consider it safe to touch.

author: Circlotron
author_rank: Super Contributor
timestamp: March 06, 2020, 05:53:26 am
content: A 12V single output power supply would be a good starting point for a cheap bench supply too!

author: langwadt
author_rank: Super Contributor
timestamp: March 06, 2020, 10:19:48 am
content: Quote from: amyk on March 06, 2020, 04:31:46 amnonsense, it'll change very little on motherboard it already has loads of switching converters

author: mariush
author_rank: Super Contributor
timestamp: March 06, 2020, 11:04:48 am
content: Quote from: DBecker on March 06, 2020, 02:55:35 amWe could go back to integrating a dc-dc regulator on the cpu substrate ... for example 20-24v in, 2v..2.5v out on the motherboard, and have a very high frequency dc-dc converter on the cpu substrate converting 2v to 0.5v...1.5v most modern processors use.Yeah, you'd lose a bit of efficiency in conversion, because you're converting twice, but the motherboard VRM may use less space or require fewer phases, and could probably work with less precision.On the other hand, cpus would be a bit more expensive but people pay 500$ for a high end cpu, so adding something like 20-50$ to such cpu wouldn't be such a big deal.... and a 45-65w tdp cpu would have a cheaper dc-dc converter on it with fewer phases, so the price difference would be less.Another option could be having a high current 3.3v VRM on the motherboard, because 3.3v is still present on the pci-e slots (up to 10w) and it's used for onboard stuff anyway (chipset, audio, network chips) and M.2 drives (they can peak at up to 3-4A of current when writing bursts of data)So you could have a 20-24v in -> 3.3v out up to 100A-150A or so (doable with 4-8 phases) then have a more basic 3.3v -> 0.5v..1.5v for cpu,,, though not sure how well mosfets would work with just 3.3v ... maybe make it 5v instead , which would be usable for usb as well...

author: bd139
author_rank: Super Contributor
timestamp: March 06, 2020, 12:01:15 pm
content: That has thermal and die size considerations that are probably not cost effective. Also not sure that would make sense with the processes they have on die.

author: tooki
author_rank: Super Contributor
timestamp: March 06, 2020, 08:05:14 pm
content: Quote from: amyk on March 06, 2020, 04:31:46 amOne word: bullshit.Planned obsolescence, as commonly understood, is almost entirely a myth anyway: for reasons of warranty obligations and reputation, no company wants their things to fail early.But the bigger thing is what langwadt already said: we ALREADY have DC-DC converters all over the boards, since modern components run on many different voltages, all well below the 12V and 5V tails they’re converting from. In a modern motherboard, very few components actually run at the PSU rail voltages.

author: Monkeh
author_rank: Super Contributor
timestamp: March 06, 2020, 08:08:41 pm
content: Quote from: tooki on March 06, 2020, 08:05:14 pmAnd even when they do run at those voltages, they often want to isolate themselves somewhat from the noisy horror that is the main supply rails. Audio is an obvious example, but not the only one.

author: tooki
author_rank: Super Contributor
timestamp: March 06, 2020, 08:18:46 pm
content: Quote from: Monkeh on March 06, 2020, 08:08:41 pmExcellent point! People forget that, in exchange for being very cheap for the amount of power they provide, computer power supplies produce extremely dirty power.

author: Red Squirrel
author_rank: Super Contributor
timestamp: March 07, 2020, 12:43:33 am
content: Quote from: NiHaoMike on March 06, 2020, 01:12:55 amThe thing with lead acid though is you can float it and don't need to balance charge it. Makes things 10x easier than lithium for online backup setups as you don't need to be concerned with current, or balance charging or BMS etc. You have a power source, a string of batteries, and a load, and you just connect the positives together and negatives together and it will run indefinitely in that configuration without needing to worry about anything other than simply monitoring performance if something does go wrong. With lithium ion the charging process is very active and you're constantly adjusting current going into each cell. Trying to do that while there is also a load is very tricky. It's doable, just more complicated.

author: tooki
author_rank: Super Contributor
timestamp: March 07, 2020, 05:25:45 pm
content: And while it's true that lithium is coming down in cost, isn't lead-acid still the cheapest type of batteries, in terms of $-per-Wh, in existence?

author: tooki
author_rank: Super Contributor
timestamp: March 07, 2020, 05:36:56 pm
content: I mean, I totally understand using lithium where size and weight is an issue. But where neither of them is, lead-acid still makes tons of sense.

author: coppice
author_rank: Super Contributor
timestamp: March 07, 2020, 05:43:02 pm
content: Does anyone know the innovation that has dramatically reduced the size of the lead acid batteries in cars over the last 30 years?

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 07, 2020, 05:59:28 pm
content: Quote from: tooki on March 06, 2020, 08:18:46 pmTrue of really cheap power supplies that shouldn't be used for anything you care about, but good ones have very low ripple.Quote from: tooki on March 07, 2020, 05:25:45 pmLarge conventional lead acid, yes, small sealed lead acid, no.My experience with batteries is that while lithium ion rarely fails completely as long as it's not abused (have one that's about 20 years old, still working great in a solar charged flashlight), lead acid will eventually fail completely even if always treated well.Quote from: coppice on March 07, 2020, 05:43:02 pmCost cutting. Hence why newer cars tend to have more problems with being parked for long times.

author: tooki
author_rank: Super Contributor
timestamp: March 07, 2020, 06:03:33 pm
content: Quote from: coppice on March 07, 2020, 05:43:02 pmBut have they? I haven't observed any such trend, and a quick online search for the batteries used in my first car (a Honda Civic) shows that the battery size in those hasn't changed at all in 30+ model years.

author: coppice
author_rank: Super Contributor
timestamp: March 07, 2020, 09:27:04 pm
content: Quote from: NiHaoMike on March 07, 2020, 05:59:28 pmModern cars have issues being parked because they have anti-theft systems, internet connections, and other electronics running 24 hours a day, which have not always been designed for super low power consumption. The battery may be quite big, but all those little bundles of electronics, left running for a couple of weeks while you are on a trip, can add up. Battery capacities haven't change that much since the 60s, as they are mostly specified around the needs of the starter motor in very cold conditions.

author: coppice
author_rank: Super Contributor
timestamp: March 07, 2020, 09:35:40 pm
content: Quote from: tooki on March 07, 2020, 06:03:33 pmI remember when the battery for even a small car was quite a pain to carry any distance. Recently, when I had to change the 40AH battery in our Honda Jazz, it was so small, light and easy to carry that it was no bother at all.

author: Circlotron
author_rank: Super Contributor
timestamp: March 07, 2020, 10:26:01 pm
content: I got my first car 43 years ago. I remember the battery very clearly. Probably the only thing that has changed is the car manufacturer specifying a smaller battery to save weight and cost. Depends on whether it is covered by the vehicle warranty whether it lasts long enough. The only real change afaik was going from the black hard rubber cases with external cell links on the top in the mid 60s to the more compact and space efficient plastic cases used nowadays. And going to the low maintenance type that had more calcium in the lead to eliminate the weekly checking of battery acid level.

author: Circlotron
author_rank: Super Contributor
timestamp: March 07, 2020, 10:31:34 pm
content: Quote from: coppice on March 07, 2020, 05:43:02 pmHow is it then that you can still buy batteries for very old cars that fit the available space perfectly, yet are neither totally oversized electrically, or padded out inside to make them big enough, like an AA cell sleeved big enough to fit in a D cell space?

author: ajb
author_rank: Super Contributor
timestamp: March 08, 2020, 05:22:15 am
content: A big factor in car battery size is also going to be the shift towards smaller and lighter engines. Most of what a battery is there to do is crank the engine, smaller engine, less cranking power required, can use a smaller battery. Also, I would be surprised if car batteries had NOT improved their capacity to size ratio in the last 30yrs simply due to the advances in fundamental manufacturing technology, like plastic molding and metal forming. I don't expect those changes to be massive, but certainly observable. You can still get older batteries probably just due to the increasing lifespan of cars leading to older cars still being around and worth making parts for. Also if you've built up a supply chain around a specific battery design, it could be attractive to stick with older, established designs just to milk the investment a bit longer.

author: David Hess
author_rank: Super Contributor
timestamp: March 08, 2020, 06:03:24 pm
content: Quote from: Red Squirrel on March 07, 2020, 12:43:33 amLead acid batteries are still balanced but using a different method. Since they are tolerant of overcharging, a slightly higher voltage "equalization charge" is applied for a brief time before the float voltage is applied.

author: Red Squirrel
author_rank: Super Contributor
timestamp: March 09, 2020, 01:59:33 am
content: Quote from: David Hess on March 08, 2020, 06:03:24 pmYeah but since that is still a voltage driven process and also does not require special monitoring of each cell it's fairly trivial to do. Typically it will be done after an extended power outage, or on a schedule. The load will see the increased voltage too, but it will normally be designed to handle it.

author: David Hess
author_rank: Super Contributor
timestamp: March 09, 2020, 02:55:41 am
content: Quote from: Red Squirrel on March 09, 2020, 01:59:33 amI have always wondered if cell balancing a lead acid battery by forcing identical cell voltages like with a lithium battery would improve operating life.

author: DBecker
author_rank: Frequent Contributor
timestamp: March 09, 2020, 05:34:40 am
content: Quote from: Circlotron on March 07, 2020, 10:26:01 pmModern engines have lower internal friction from better machining and lighter oil. They have geared starter motors which can turn over the engine even with sagging voltage.And a modern ECU is vastly better at starting an engine within one or two compression strokes. Crank position used to be measured from VR sensor (pick up coil) measuring a "missing tooth" reluctor wheel in the crank with evenly spaced teeth with a gap, and perhaps a camshaft sensor. That required a minimum speed to generate a usable signal and perhaps two full turns of the crank to know the position. Today Hall sensors allows a usable signal down to 0 RPM. That allows the ECU record the crank position during engine shutdown, and accurately detect a slowly moving crank. Some engines (e.g. GM) use an irregular tooth pattern on the reluctor wheel, which lets the crank position be quickly confirmed. Fuel injectors form an ignitable mixture with minimal airflow, and multiple sparks ignite an unevenly mixed intake charge.As for technology improvements in the battery itself... I haven't seen an increase in power density, energy density or longevity since the 1980s. I have a sealed AGM that is nearly unusable just a few months after its 3 year warranty expired, and just replaced the battery in another car after 4.5 years. That's from a small sample size, but it points out that the automotive batteries haven't really improved.

author: DimitriP
author_rank: Super Contributor
timestamp: March 09, 2020, 10:59:26 am
content: QuoteLet's see...google has been doing it since at least 2009https://www.cnet.com/news/google-uncloaks-once-secret-server-10209580/So either someone from google got hired by Intel , or Intel independently decided to catch up.They might also have decided to stop relying on varying quality third party power supplies.

author: coppice
author_rank: Super Contributor
timestamp: March 09, 2020, 11:30:08 am
content: Quote from: DimitriP on March 09, 2020, 10:59:26 amRack mount servers moved to 12V only power supplies long ago. The present discussion is about the desktop catching up.

author: Psi
author_rank: Super Contributor
timestamp: March 09, 2020, 11:37:03 am
content: Yep, i'm all for single voltage PC power supplies.Although having a separate low current standby voltage in addition to the high current feed does make sense.It seems pretty wasteful to design all PC PSU to do +3.3 at x Amps, +5 at y Amps and +12 at z Amps etc.. and then have all the motherboard manufactures decide to use some of that available power on some of the rails.And it would be super cool if they had the spec allow a voltage range that matched up to a number of lipo cells between flat and charged.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 09, 2020, 02:08:24 pm
content: Quote from: Psi on March 09, 2020, 11:37:03 amGiven that it's hard to design a switching PS that is both very efficient at high and low currents, that could make sense. Unfortunately, I don't know how many people put their desktop PCs in standby instead of just leaving them on idle (or switching them off altogether when they are done), so I don't know how much impact that would have in practice. I for one never used to put my desltop PCs in standby (and it was often buggy in the past depending on your hardware and OS), but I've been doing so for the past year or so and it works very well - saves a lot of power indeed.Either way, the low current rail could still be 12V. I haven't read Intel's spec carefully, but I don't think anything would prevent to do this with a single rail with a little more "intelligence" in the PSU. It could switch automatically to different blocks in the PSU depending on the load - that would fit the bill without having to make the spec more complex or having to deal with more voltages/or do the switch-over on the motherboards if it can be done in the main PSU.Quote from: Psi on March 09, 2020, 11:37:03 amGiven that on modern motherboards, much of the current is already taken from the +12V rail (CPU, GPU...), this all looked like a natural move.Quote from: Psi on March 09, 2020, 11:37:03 amI'm not sure what purpose there would really be, I think they are mostly targetting desktop computer. Why would you want to power them with LiPo batteries?

author: mariush
author_rank: Super Contributor
timestamp: March 09, 2020, 02:39:50 pm
content: ATX was invented 20+ years ago... and it's still going.I think it would be somewhat shortsighted to standardize some voltage based on the number of cells of a particular battery technology. Who knows, 5-10 years from now we could have totally different battery cells based on nanotubes or hydrogen cells or graphene (ultracapacitors)12v seems reasonable and I mentioned several times that 20v (chosen in the usb power delivery) sounds like a good compromise (would allow use of solid polymer capacitors rated for 25v or ceramic capacitors, mosfets should still work relatively fine in vrms and so on.I feel like a low voltage should remain to make low power devices efficient.. we now have Intel and Ryzen laptop processors on 7nm-14nm that consume 10-15 watts while doing actual work, so it wouldn't surprise me if a few years from now we'd have processors consuming less than 5w on average. Such tablets and laptops could probably work better with lower voltages like 7.4v (2 lithium cells in series) or whatever new battery technology will be (what if future battery cells will be 1.8v ..2.4v each...)I don't see why we could not have the standby 12v from an offline switcher (let's say 1-2A max and 90+ efficient) and 3-5 seconds after motherboard orders start up, you could have a mechanical relay or something in the power supply switch the 12vSB wire to the actual 12v dc-dc converter in the power supply, which is designed for 30-50A or even more, and which can do maybe upwards of 95% efficiency.

author: tom66
author_rank: Super Contributor
timestamp: March 09, 2020, 03:27:19 pm
content: SMPSes are more efficient when designed for one output voltage, ideally with a load that is relatively close to the rating of the power supply.Having multiple rails complicates efficient design, because you need to handle crossload conditions and regulation across all rails. Many modern power supplies now use post-DCDC conversion, generating the -12V, 5V and 3V3 rails from the +12V supply, which eliminates the crossload issue. But as others have stated, this then needs to be distributed to the motherboard over lossy cables. Why not just distribute it from the motherboard? The majority of high-power consumers are located there.I wouldn't be surprised to see if the next SATA spec completely omits +12V from the power supply and drives run purely on +5V and/or +3V3 to reduce wiring harness size.Another side benefit is, if the ATX spec allows it, the 12V rail might be able to go as high as 13.8V for a float-charged lead-acid battery. I believe that's the technology Google use for some of their custom-built servers: each server has its own backup battery, instead of relying upon a larger UPS/generator with double-conversion.

author: madires
author_rank: Super Contributor
timestamp: March 09, 2020, 05:15:27 pm
content: The ATX specifiaction states ±5% for the 12V rail.

author: tunk
author_rank: Super Contributor
timestamp: March 09, 2020, 05:21:56 pm
content: I just opened a 5 year old Dell all-in-one PC and the PSU only had 12V.

author: tom66
author_rank: Super Contributor
timestamp: March 09, 2020, 06:34:17 pm
content: Quote from: madires on March 09, 2020, 05:15:27 pmWas referring to the possibility of a modified or relaxed ATX spec with a 12V range of 11.5V ~ 14.4V. I've found that at least one motherboard will operate on a relatively wide range of operating voltages but a HDD might not, as it began overspeeding and shut down (I modified an old ATX power supply on a Dell PC of mine to have an adjustable 12V rail out of interest, though this was many years ago.)

author: Psi
author_rank: Super Contributor
timestamp: March 09, 2020, 10:37:04 pm
content: Quote from: SiliconWizard on March 09, 2020, 02:08:24 pmIt would be much more efficient/cheaper/simpler to connect batteries to the input of the motherboard than use a 110/220v inverter.Imagine if you could simply add 3x high current Li-on 18650 cells in your computer case for a simple 1-2 minute UPS so you can save your work.Monitor would need some sort of backup power too though, no point in pc running if you can't see anything

author: tooki
author_rank: Super Contributor
timestamp: March 09, 2020, 10:55:59 pm
content: LiPo isn’t the ideal technology for this. They don’t like being stored at full charge, they can’t be trickle charged, and they’re fairly expensive. The reason for LiPo’s popularity is energy density for portable devices. They make NO sense for stationary items where weight and size aren’t primary concerns.A 12V lead-acid or 10 NiMH cells (of the kind specially made for this type of application) would make way more sense.

author: Circlotron
author_rank: Super Contributor
timestamp: March 09, 2020, 11:01:54 pm
content: Quote from: mariush on March 09, 2020, 02:39:50 pmMakes me think of vacuum tubes that after a while settled on mostly 6.3V filaments so they could operate off a 6 volt 3 cell lead acid car battery. That standard has been around for nearly a hundred years.

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 10, 2020, 02:47:45 am
content: What I would like to see on motherboards and GPUs is a hookup to the PROCHOT line, to instantly throttle the frequency to the lowest level when running on backup power. That can make a huge savings in the battery needed for backup. I'm surprised the data centers haven't looked into that, where in addition to the batteries, downsizing the backup generator is more huge savings.

author: Berni
author_rank: Super Contributor
timestamp: March 10, 2020, 07:22:31 am
content: Quote from: NiHaoMike on March 10, 2020, 02:47:45 amDatacenters have a different use case.They want to stay fully operational no matter what because there costumers get very grumpy when the service drops out. The contracts they signed with there costumers contain the agreed upon uptime. So suddenly throttling down there compute performance to 25% would likely not be seen by the costumers as being fully operational and would count towards some sort of downtime. Failing to meet contract obligations is more expensive that the large piles of diesel fuel they are pouring into those generators.For us home users its a different thing. We just need the thing to shut down safely without loosing data or messing up the filesystem.