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| What is the motivation of intel to want PSUs that are 12V only? |
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| mariush:
--- Quote from: DBecker on March 06, 2020, 02:55:35 am ---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. --- End quote --- We 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... |
| bd139:
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. |
| tooki:
--- Quote from: amyk on March 06, 2020, 04:31:46 am ---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. --- End quote --- One 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. |
| Monkeh:
--- Quote from: tooki on March 06, 2020, 08:05:14 pm ---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. --- End quote --- And 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. |
| tooki:
--- Quote from: Monkeh on March 06, 2020, 08:08:41 pm ---And 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. --- End quote --- Excellent point! People forget that, in exchange for being very cheap for the amount of power they provide, computer power supplies produce extremely dirty power. |
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