No one knows any alternatives?

I'll just order these, then.

I've run old rigs on various modern PSUs without trouble. It's only the most demanding stuff, like a high-power Athlon XP on an old 5v motherboard, that can be troublesome. But I don't think I've had any problems even with that sort of setup....

I have a PC Power & Cooling 430W (Seasonic rebrand) and a Seasonic S12II 520W. I was using a Seasonic 300W for awhile years ago too. I did have a couple of old 5v powerhouses, a Enermax Noisetaker 475W and a really old PCP&C 300W, but they both died of component failures due to age I suppose.

So the Seasonic should be a good choice, then? Have you ever noticed a noisy sound output from the PC with S12II, by any chance?

Because that's the main reason I'm replacing my PSUs... I currently use a no-name 550W OEM unit in the P4 system which I pulled from an other PC. The P3 is powered by a 250W Lite-on. The first has about 250mVpp ripple at 12V. The Lite-on's got 200mVpp noise on 12V, though most of that is beyond the audio spectrum. I was impressed by the Seasonic's 20-25mVpp ripple on 12V, in theory that might give me a 20dB improvement in noise levels!

Well, anyway, I already ordered them. Had to do that before 22:00 for next-day delivery 😀

I've played a lot of games on systems built on that S12II and have played with headphones. No audio issues AFAIR.

PC Power and Cooling made some very solid power supplies back in the day. If you can get your hands on one of these, it would be great. They may even be able to help you source one. I had to replace a fan on an older Cyrix processor and they helped me find a chipset fan that was almost the exact same.

jwt27 wrote:

My 7800GS card in the P4 system does require 21A at 12V, or so the manual says... The 430W Seasonic offers 17A per rail (there's 2 of them). Will I run into trouble if I connect the graphics card on one rail, and everything else on the other?

edit: it seems the S12II has only one solid cap, one Rubycon and the others are Chemi-con. And only one 12V rail instead of two. I assume this rail can deliver 34A then. The 21A rating for the 7800GS seems a little optimistic anyway... that's 254 watt for just an AGP card!

I really wise that people wouldn't quote min psu requirement for a single graphics card in that matter especially Nvidia as it is not accurate except for a whole system when the card barely needs more than 5 or 6 amps to run full load. That card and a P4 don't use that much at full until one starts overclocking the cpu, the graphics card won't top much beyond 105w max if even 90w. So don't quote amps like that unless it is whole system or go by what will actually be needed. There is a small period when the system is first started where the loads are higher but that is in milliseconds.

New PSUs are installed and running 😀

I almost thought the 430W one was DOA... After installing it, windows started spitting out a lot of errors and bluescreens, including one I've never seen before. Turned out the BIOS settings were reset and defaulted to CAS 2.5... Setting it back to 3 fixed it.

Some ripple measurements from the 380W version:

- Switched on manually, nothing attached:
5V: 250mV
12V: 125mV

- Installed, switched on:
5V: 55mV
12V: 70mV
Not exactly the 20-25mV I've seen on reviews, but then most of this is somewhere in the MHz range which USB scopes (used by all PC hardware reviewers) don't pick up. And the caps on this mainboard are like, 15 year old Chinese crap.

- Harddrives switched off through APM:
5V: 50mVpp
12V: 55mVpp
Major noise source here. After switching these off most of the audio-frequency noise is gone.
Just for kicks, try this: turn up your speakers to eleven, and run a speedsys HDD test 😉

nforce4max wrote:

jwt27 wrote:

My 7800GS card in the P4 system does require 21A at 12V, or so the manual says... The 430W Seasonic offers 17A per rail (there's 2 of them). Will I run into trouble if I connect the graphics card on one rail, and everything else on the other?

edit: it seems the S12II has only one solid cap, one Rubycon and the others are Chemi-con. And only one 12V rail instead of two. I assume this rail can deliver 34A then. The 21A rating for the 7800GS seems a little optimistic anyway... that's 254 watt for just an AGP card!

I really wise that people wouldn't quote min psu requirement for a single graphics card in that matter especially Nvidia as it is not accurate except for a whole system when the card barely needs more than 5 or 6 amps to run full load. That card and a P4 don't use that much at full until one starts overclocking the cpu, the graphics card won't top much beyond 105w max if even 90w. So don't quote amps like that unless it is whole system or go by what will actually be needed. There is a small period when the system is first started where the loads are higher but that is in milliseconds.

They probably calculated the amp rating for a complete system on full load, with some safety margins. I looked up the 7800GS's TDP and it's "only" 75W. I think the 380W model would have been sufficient for the whole system.

Seasonic S12II are veteran but solid designs, with nice voltage and ripple regulation and stuffed with good Chemicon jap lytics (solid caps are great for mobos but not so good for several tasks inside a PSU). Both are way overkill for your applications (the 430 can in fact handle 500W, don't sweat about GPU draw) so I'd say you're very well served.

The real DC draw from a PIII system is ~80W. A P4 Preshott @ 4.25GHz draws ~250W DC full burner.