20A on a 5V rail is a bit on the low side, however, considering it's a Sempron I'd say go for it, just don't overclock it.

I'd also like to recommend this video from PhilsComputerLab:
https://www.youtube.com/watch?v=efK7mw8eYiE

This is one of the more challenging builds as it's one of the last motherboards with CPU power via 5V, and a 'hot' CPU on it. The CPU's max power draw is 62W. That's 12.4A net at the CPU. Allowing for 80% efficiency of the DC-to-DC regulators means the board will draw 15.5A for the CPU alone. Then you're adding a GPU that draws 47W/35W. I'm not up to speed on exactly how the AGP 2.0/30 voltages are derived on these boards, but at the very least there's 2A on the slot at 5V regardless. That pushes you up to 17.5A. Then you have PCI and drives... I'm confident this system will draw over 20A on 5V alone (disregarding whatever it does on 3.3V, 1.5V annd 0.8V), so this PSU will not be sufficient. I would suggest at least 30A on 5V for this system.

That gives two options:
1) a good vintage PSU, ~300W should do the trick. Risks: this was also capacitor plague era, so you should check caps thoroughly.
2) a massively powerful modern PSU with a beefy 12V->5V DC-to-DC regulator onboard.

The latter is the safer option, but not cheap. The former the more period-correct elegant one, but has an element of risk. In both cases, go for quality. Coolermaster isn't awful but at best they're lower-end mainstream stuff. I personally prefer the bigger OEM vendors' supplies as you're not paying for bling and marketing there. I'm not enough up to speed on current ones to do recommendations there, but with vintage stuff FSP is my go-to brand as it's easy to find and generally very good quality (around here AOpen-branded FSPs are commonest) - their 300W PSUs weigh a ton, and that's not cement either. They can however suffer from bad caps, but at least they're worth re-capping.

@dionb
your calculations are correct, however you're considering CPU's max power at 62 Watts, which should be only the case when running programs like Prime95. During actual gaming the power draw should be lower, as it is also stated on cpu-world.com: Typical Power 49.4 Watt.

The CPU's max power draw is 62W

That's maximum power dissipation though, not power draw.

During actual gaming the power draw should be lower

Yes, you can't load both GPU and CPU simultaneously at their peak power.

Thank you very much for answers 😀

Also you can decrease CPU voltage to 1.4-1.5v.

aaronkatrini wrote on 2021-02-25, 11:03:

@dionb
your calculations are correct, however you're considering CPU's max power at 62 Watts, which should be only the case when running programs like Prime95. During actual gaming the power draw should be lower, as it is also stated on cpu-world.com: Typical Power 49.4 Watt.

True, but you always want a PSU to be able to handle the max draw that a system could theoretically do, not to go up in smoke if it does perchance actually draw it. For more continuous use, you're best aiming for max 80% of peak PSU limit anyway.

Big question is whether that "500W" and "5V 20A" is peak or sustained power. Better brands generally quote sustained power, cheaper ones generally quote absolute peak. I don't know what Coolermaster does. Either way, 20A is cutting it fine here, too fine for my tastes.

You can still sometimes find new PSUs with decent 5V rails.
There are several Hercules branded PSUs floating around with beefy 5V rails.

DNSDies wrote on 2021-02-25, 16:54:

You can still sometimes find new PSUs with decent 5V rails.
There are several Hercules branded PSUs floating around with beefy 5V rails.

Hercules was the worst reviewed and most explosive PSU to go through Johnny Guru.

Modern PSUs will sometimes overdeliver on the 5v rails but you are taking a bit of a risk. If you already have the parts on hand (not buying them), I would just try it. Install an OS, run prime95 and furmark concurrently for an hour, and see if make it through. The only thing you have to worry about it potentially damaging the PSU, but it should have trip current and over voltage protection to protect your vintage gear.

Socket A is pretty hard. Socket 478 uses 12v for everything and is a lot easier to work with.

My experience is very similar to dionb's; A lot of the Fortron Source (FSP) or Aopen power supplies can be sold quite cheaply used, they're reliable (imo) and given that many are from the era of the Athlon, they've often got 30A on the 5v rail. PC Power and Cooling and Seasonic are also good to look out for.

I bought an FSP-made Aopen-branded FSP350-60PN and with the 120mm fan it's a great power supply.
I've also got a SilenX power supply that someone gave me years ago, it's 400w and has a huge 40A 5V rail, again made by FSP.

One thing to consider is that in the era where big 5v rails were needed, 400 watts was a huge power supply, those should be safe as long as you go for reliable brands like SeaSonic or FSP.
But even then, I think the regulation isn't quite as good as modern PSUs, and with a high amperage 5v rail, a short is less likely to be detected fast enough to avoid damage so be careful when wiring things up.

those should be safe as long as you go for reliable brands like SeaSonic or FSP.

FSP PSUs in question are mostly designed for OEM. They have acceptable quality, but nothing more than that.