Gateway Pentium 4 ATX power supply with -5 volt?

[DuluthMnNice]

Hi, thanks for being here Tried to boot this barn find of a PC, came up with 768MB RAM running Windows XP Black edition! Did not run long, OTOH. I immediately suspected the power supply, and will try others, starting with the one that came with it in a custom case. Smelled like cigs so I used a much more modern ATX, thinking that it was more likely to run well with a newer supply. I was googling around and did find the manual, and pinouts, and remembered running into an oddity with older ATX PSU having a -5v rating(possibly only Gateway proprietary), in my previous experience and chatting with a work colleague, I'd noticed the PSU tester would show a -5 volt LED that would only show up on certain older supplies, and not the modern ones. Bingo, I thought! maybe this is it. and I suppose it could be, but I could not find it anywhere on the web?! I do not have a PSU tester that I know where is at the moment, but the initial plan remains to test the one that came with the build for starters, and hope it works.

Machine is a Gateway P4 1.6GHZ using D845PT motherboard. I did try swapping/exchanging/reseating RAM, disconnecting hard drive (only drive connected currently for testing anyway), and taking the video card out with no fresh results. Will update you all on progress, and would appreciate any input on this apparently strange mystery, as the only clue was in the manual which states that "A standard ATX power supply will not work, you must use ATX12V-" which doesn't google either. Could be bad caps IMO, even though they look good, I'm well aware, and I don't want to mess around with the CPU clips as they nearly always broke on me when I was messing around years ago, maybe 1 out of 5 metal clips(there's two on it) survived gentle prodding. I will change out the CPU cooler to a different system as soon as I can if it turns out to work but the IHS coupled with the thermal transfer glue they used to use on these is likely not the problem, even though I may actually have a faster one for it, I wanna get this dell case that had a P4 in it originally running with some ludicrous 3dfx action rolling (and yes, I have verified the power switch works, changed it out myself.

 

[pbirkel@gmail.com]

The –5 Vdc rail supplies the ISA bus (pin B5) -- it's in the ISA specification.
Analog boards may use it, historically (e.g., FDD data separator circuits).
Unless you have a quite unusual (and very old) motherboard that -5 Vdc rail is like an appendix ... your computer can live without it.

Helpful reference: https://www.informit.com/articles/article.aspx?p=30273&seqNum=2

 

[DuluthMnNice]

The –5 Vdc rail supplies the ISA bus (pin B5) -- it's in the ISA specification.
Analog boards may use it, historically (e.g., FDD data separator circuits).
Unless you have a quite unusual (and very old) motherboard that -5 Vdc rail is like an appendix ... your computer can live without it.

Helpful reference: https://www.informit.com/articles/article.aspx?p=30273&seqNum=2

Thanks, that's helpful for the future. Went ahead and changed the power supply, took out the card reader that I had plugged into the USB header that I had also tested previously working, then tempted fate with the metal clips on the CPU, and this time they both came off and went on fine, this time covering a 2GHZ P4. Tried the "recovery" option, after using the clear BIOS and then back to default jumper location - three positions. No changes, I'm stumped with this.

 

[DuluthMnNice]

Incidentally the original power supply from 2012 has the -5 rail.

 

[DuluthMnNice]

I've successfully defeated Boolean searching to display results for -5 volts in a PSU, and found it is not likely to be relevant, as I do not have ISA slots, unless some onboard devices are this old, which I find to be pretty likely. Board seems fried, but I may take it out and clean as a last resort.