Max 5v current alone does not tell whole story. Most inexpensive power supplies are group regulated and are intended for certain combination of 5v and 12v load. If you load such PSU with 5v primarily, even if rated 5v current is high, voltages may drift (5v goes down, 12v up) and it may either shut down to prevent damage or it may just continue outputting way out of spec voltages.

S370 does not require a lot of power. Look for DC-DC based power supply (basically 12v PSU + 12V->5V DC-DC converter for 5V) with decent 5V rating, around 15-20A are common and would be sufficient for S370. In this case atypical load, like mostly 5V would not matter and there should be no issues as long as you stay within limits in terms of current.

You'll have to dig up which one is which in reviews and such (And it can be a pain), as manufacturers usually do not tell this in specs.

Also do not bother about whole 80+ thing. It only affects efficiency and has absolutely nothing to do with quality or reliability. So choosing PSU with higher efficiency you are saving a few watts of power, especially in case of stuff like s370 which has pretty low power consumption. And that's it - no other benefits.

As for failures... could be anything. May be PSU did something bad, may be the controller just decided to die. It happens.

Archer57 wrote on 2025-06-13, 04:19:

Max 5v current alone does not tell whole story. Most inexpensive power supplies are group regulated and are intended for certain combination of 5v and 12v load. If you load such PSU with 5v primarily, even if rated 5v current is high, voltages may drift (5v goes down, 12v up) and it may either shut down to prevent damage or it may just continue outputting way out of spec voltages.

The P450B is indeed a single 12V rail PSU. Not sure about the other one. I usually connect only the bare minimum peripherals such as a PS2 mouse/kb. For hard disk I always use a sd to ide converter. So is there any other way to know if the load is properly distributed?

Archer57 wrote on 2025-06-13, 04:19:

S370 does not require a lot of power. Look for DC-DC based power supply (basically 12v PSU + 12V->5V DC-DC converter for 5V) with decent 5V rating, around 15-20A are common and would be sufficient for S370. In this case atypical load, like mostly 5V would not matter and there should be no issues as long as you stay within limits in terms of current.

Any suggestions for such types of power supplies?

This thread discusses tbe subject matter.
I need help with picking a psu for my Pentium 3 build?

If you do decide to try a modern PSU, always check actual specs of the specific unit you are buying. PSU manufacturers love to introduce silent (or nearly so) revisions of their models. Newer revisions of a given model may have lower capacity 5V and 3.3V rails than older ones, even high end units with DC-DC converters in those secondary rails.

Socket 370 CPUs use +12V (and not an awful lot of it), so pretty much any contemporary PSU will be fine. I've even used 80W picoPSUs such as https://mini-box.com.au/product/picopsu-80-wi-32v/ without too much trouble, as long as the video card isn't too demanding with +5V. A 1.4Ghz Tualatin will stress it a bit, though reducing the FSB down to 100Mhz or 66Mhz is perfectly fine.

DEAT wrote on 2025-06-13, 07:13:

Socket 370 CPUs use +12V (and not an awful lot of it), so pretty much any contemporary PSU will be fine. I've even used 80W picoPSUs such as https://mini-box.com.au/product/picopsu-80-wi-32v/ without too much trouble, as long as the video card isn't too demanding with +5V. A 1.4Ghz Tualatin will stress it a bit, though reducing the FSB down to 100Mhz or 66Mhz is perfectly fine.

yep
50mA to PWM controller + 50mA to COMport.
Well, the fan also consumes 150 mA.

the video card

FX5700 is fully powered by +3.3V
All 30+Watts.
Radeon 9600 - almost the same. (not counting 2-3W for memory buffers.
Why? - well, that's how they did it back then)
9800 - 80% to 5+3.3V
https://github.com/TeHSiGGi/agp-power-monitor … RENCE_VALUES.md
Well, Tualatin itself - (30+ Watts) + (losses due to the efficiency of the VRM) from +5V rail.
Chipset+RAM - ~25W from +3.3V

shevalier wrote on 2025-06-13, 09:07:

yep 50mA to PWM controller + 50mA to COMport. Well, the fan also consumes 150 mA. […]
Show full quote

DEAT wrote on 2025-06-13, 07:13:

Socket 370 CPUs use +12V (and not an awful lot of it), so pretty much any contemporary PSU will be fine. I've even used 80W picoPSUs such as https://mini-box.com.au/product/picopsu-80-wi-32v/ without too much trouble, as long as the video card isn't too demanding with +5V. A 1.4Ghz Tualatin will stress it a bit, though reducing the FSB down to 100Mhz or 66Mhz is perfectly fine.

yep
50mA to PWM controller + 50mA to COMport.
Well, the fan also consumes 150 mA.

the video card

FX5700 is fully powered by +3.3V
All 30+Watts.
Radeon 9600 - almost the same. (not counting 2-3W for memory buffers.
Why? - well, that's how they did it back then)
9800 - 80% to 5+3.3V
https://github.com/TeHSiGGi/agp-power-monitor … RENCE_VALUES.md
Well, Tualatin itself - (30+ Watts) + (losses due to the efficiency of the VRM) from +5V rail.
Chipset+RAM - ~25W from +3.3V

Nice! I had been looking for that kind of info a while back. Thank you.
EDIT: This tbe thread from that time. Question about Geforce FX 5900 current draw per rail

On the whole system power consumption front, here is the data I got from my Tualatin 1400MHz system at the time. Re: What modern PSU powers your Pentium3 setups? EDIT: This whole thread might be interesting too.