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Comment by opencl | Hacker News Reader

Because nobody makes 24V power supplies for computers, they'd have to convince the whole industry to agree on new PSU standards.

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> they'd have to convince the whole industry to agree on new PSU standards.

We already have a new PSU standard, it's called ATX12VO and drops all lower voltages (5V, 3.3V), keeping only 12V. AFAIK, it's not seen wide adoption.

It's also of no use for the problem at hand, PCIe already uses 12V but that's way too low for the amount of power GPUs want.

It's not great. Dropping 5V makes power routing more complicated and needs big conversion blocks outside the PSU.

I would say it makes sense if you want to cut the PSU entirely, for racks of servers fed DC, but in that case it looks like 48V wins.

There are already huge conversion blocks outside the PSU. That's why they figured there's no need to keep an extra one inside the PSU and run more wiring everywhere.

Your CPU steps down 12 volts to 1 volt and a bit. So does your GPU. If you see the big bank of coils next to your CPU on your motherboard, maybe with a heatsink on top, probably on the opposite side from your RAM, that's the section where the voltage gets converted down.

Those are actually at the point of use and unavoidable. I mean extra ones that convert to 5V and then send the power back out elsewhere. All those drives and USB ports still need 5V and the best place to make it is the PSU.

Why is the PSU the best place to make 5 volts? In the distant past it made sense because it allowed some circuitry to be shared between all the different voltages. Now that is not a concern.

The motherboard is cramped, the PSU has a longer life time, and routing power from PSU to motherboard to SATA drive is a mess.

Yup, exactly. The VRMs on my Threadripper board take up quite a bit of space.

24VDC is the most common supply for industrial electronics like PLCs, sensors etc. It is used in almost every type of industrial automation systems. 48VDC is also not uncommon for bigger power supplies, servos, etc.

https://www.siemens.com/global/en/products/automation/power-...

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