You build it, I'll buy it.

if you require a massive 25+ volts current on the 5v rail.

Realistically speaking, no such thing is required in most cases. 30-35A is more than overkill for any 5V oriented system, outside of really extreme overclocking of some super crazy setup with massive amount of storage devices.

I actually have done this for my OLD NAS box.

I took the PCI-e power. the +12v went to 6x 5v buck regulators. Each regulator provided 5v to 2 hard drives.So each pci-e 6-pin connector powered 12 hard drives. I had two of these cables and it worked perfectly for years, until I got a proper rackmount chassis. Just search ebay for something like: " DC-DC 3A Buck "

Modern power supplies work EXACTLY the same anyway. That's how they get the 90%+ efficency.

The Serpent Rider wrote on 2020-09-26, 23:42:

if you require a massive 25+ volts current on the 5v rail.

Realistically speaking, no such thing is required in most cases. 30-35A is more than overkill for any 5V oriented system, outside of really extreme overclocking of some super crazy setup with massive amount of storage devices.

I was thinking of the most demanding platform for 5v: socket A.
Athlon: 70W = 14A
Graphics: 25 W = 5A
4 PCI cards, 1A each = 4A
4 drives, 1A each = 4A
Motherboard = 3A

Total 30A. Probably not too far off.

Yes I know these are extreme values, probably not occuring all at once, but a little overhead feels safe.

Yes it is possible. However:
Re: Modern PSU for Pentium 3 what 5V xxA ?

waterbeesje wrote on 2020-09-27, 00:04:

Total 30A. Probably not too far off.

Looking at what my Dual P-!!! @ 1GHz takes it's about 50% off at least. Either way I guess you could use such as https://www.ebay.co.uk/itm/173429611642

waterbeesje wrote on 2020-09-27, 00:04:

I was thinking of the most demanding platform for 5v: socket A. Athlon: 70W = 14A Graphics: 25 W = 5A 4 PCI cards, 1A each = 4A […]
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The Serpent Rider wrote on 2020-09-26, 23:42:

if you require a massive 25+ volts current on the 5v rail.

Realistically speaking, no such thing is required in most cases. 30-35A is more than overkill for any 5V oriented system, outside of really extreme overclocking of some super crazy setup with massive amount of storage devices.

I was thinking of the most demanding platform for 5v: socket A.
Athlon: 70W = 14A
Graphics: 25 W = 5A
4 PCI cards, 1A each = 4A
4 drives, 1A each = 4A
Motherboard = 3A

Total 30A. Probably not too far off.

Yes I know these are extreme values, probably not occuring all at once, but a little overhead feels safe.

The most demanding is dual SoA, at least the early boards without ATX12V connector (which made life a lot easier), I'd say they could top out over 35A.

However I don't think you need to take drives into account - if I understand your proposal correctly, it would run off the ATX(12V) connector, which means that 5V for Molex would come from the PSU's own 5V line; this one only needs to feed motherboard, CPU(s) and cards.

@dionb; Drives will get the Molex indeed. So basically around 20-25A will be plenty enough. Dual soA is is not planned :p

@red-ray: The converter n your link might do the trick 😀 it provides 10-30A it says, so two of them might be ok. Still steep on the price... But I'll keep looking for this stuff.

waterbeesje wrote on 2020-09-28, 14:26:

@red-ray: The converter n your link might do the trick 😀

After posting I am now wondering how good the regulation is, you need to check this. I suspect a single 10A one would be more than enough for the disks with the MB using +5 directly from the PSU.

Further I just checked what my Athlon system uses which is way less than 30 A.