What is your current Make/model 450w PSU ? Going to a 500w is iffy because the total wattage is just one part, the quality of the PSU is another. Add in the specs: PSU total Amps supplied by each voltage line plus the total of the 3.3v 5v and 12v combined. The Antec 480w Truepower (as an example) I have can do 30a on 3.3v, 38a on 5v, 22a on 12v. ..but the combined total on those three is 460 watts which I have yet to max out on any AGP system. There are also PC Power and Cooling, FSP, and some other brands that also have very high combined wattage and are good quality. Unfortunately none of the really good ones are made any more.
added: For the Antec that means each main voltage rail could be pushing near 22amps to hit near 460watts. Usually you calculate the needed amps and then find a PSU that supplies at least double that...

The one that I found at the time I was building my Pentium III build was an Antec VP450. Just recently I recapped the entire thing (because they used cheap capacitors according to badcaps.net), but that didn't seem to do much. If anything, it seemed to make the problem worse.

I'm seeing good reviews for an EVGA 600W power supply, even though my system can't use the 6 SATA cables that it gives, unless I decide to integrate some SATA drives for Windows XP.

https://www.google.com/shopping/product/92038 … HRknApkQ8wII6gQ

Which cards are you using ? I use my pentium 2 build with 7 cards too without any problem and my PSU must be a 150w or 200w ^^

Deksor wrote on 2020-06-12, 02:22:

Which cards are you using ? I use my pentium 2 build with 7 cards too without any problem and my PSU must be a 150w or 200w ^^

Well, two of the cards that I use are tentative at the moment, because I'm trying to test out the best card (that uses a feature connector) for my VR helmet:

• AGP: nVidia geForce FX 5500 (For mid-2000s games)
• PCI: (This slot is blank as of this post, for a testing an incoming video card that can provide video output for the VR helmet)

Although I might be swapping card strengths (i.e. The less powerful card goes in the AGP slot, etc.) if it works for later.

The other 5 are fine:

• PCI: Sound Blaster Audigy 2 ZS (For MIDI Keyboard I/O + mid-2000s games and movies, because I have a 4.1 surround sound system)
• PCI: Hauppauge WinTV (44371) Card (For later video recording/video input)
• ISA: VFX1 VIP Decoder Card (Cable-attached to whatever card will go in the blank PCI slot)
• ISA: SB16 CT1740 (For MS-DOS Gaming + FM Synth MIDI Playback + Joystick Port)
• ISA: Etherlink 3C509B-TP ISA PNP Ethernet Card (For retro system updates/Zandronum on Win XP)

I recently did a Voltage Regulator chip-swap on the motherboard that allows me to use a more powerful processor. (It works, though, AND it actually lets me use the system with my 866MHz Pentium III with a steady and stable 133 MHz FSB!)

I've also been able to figure out something else. Everything goes to crap as soon as I have all 7 slots filled. I can use 6 cards, as the slot above is blank right now, but as soon as I fill in that final slot, I lose stability, and the system won't even boot at times. Maybe I do need 500 Watts.

Why do you think it's the PSU causing the instability? Or power in the first place.

The GfFX5500 is a big draw but the rest of those cards are almost insignificant in terms of power draw. Simple test would be to temporarily replace the FX5500 with something lighter (Gf2MX, TNT, whatever). If that improves stability with 7 slots, it's probably power-related, but not necessarily PSU. You did a VRM mod, that might have had unintended consequences for the bus power. What motherboard are we talking about here?

If it is power, don't obsess with big numbers overall. This is an old P3 system that draws power for both PCI bus and CPU from the 5V line - hence my concern about the VRM mod. You need a lot of current on 5V, but the big modern PSUs you're looking at are designed for systems that draw PCIe and CPU from 12V, usually with a minimal 5V line only for legacy stuff. A 300W 2000-ish PSU will have a bigger 5V line than a 900W modern one. If you are hitting 5V limitations, you might want to look for that kind of PSU instead.

If that doesn't change anything, it's not power. Maybe your BIOS can't handle the PnP resource allocation to so many cards and stuff ends up conflicting.

I'm a dope. (I was trying to measure the amperage with a multimeter, but I guess I don't know how to do that properly yet, cause I tripped the safety on the power supply at most 3 times. I think it's because I was trying to measure it like one would normally measure voltage.)

It says the amperage right on the power supply, and TBH, it seems REALLY weak! (Based on what I've seen recently for ATX power supplies. EDIT: Yeah, there's one that I found that is 21A on 5V! Mine is just 15A!)

dionb wrote on 2020-06-12, 10:50:

If that doesn't change anything, it's not power. Maybe your BIOS can't handle the PnP resource allocation to so many cards and stuff ends up conflicting.

Also, to clarify, I not only had stability issues, but multiple times, the computer just would not progress past POST, even though it seems like it's fine. (i.e. the computer does turn on and it beeps as if the POST has succeeded, but the screen stays blank, and nothing progresses. In fact, it beeps quite a bit too soon for the POST to be legitimate.)

T-Squared wrote on 2020-06-12, 17:11:

I'm a dope. (I was trying to measure the amperage with a multimeter, but I guess I don't know how to do that properly yet, cause I tripped the safety on the power supply at most 3 times. I think it's because I was trying to measure it like one would normally measure voltage.)

It says the amperage right on the power supply, and TBH, it seems REALLY weak! (Based on what I've seen recently for ATX power supplies. EDIT: Yeah, there's one that I found that is 21A on 5V! Mine is just 15A!)

20200612_120630.jpg

By comparison my 300W AOpen/FSP FSP300-60BT(12V), a 300W PSU, is rated for 30A on 5V. I have a 350W PSU somewhere that does 50A on 5V.

dionb wrote on 2020-06-12, 10:50:

If that doesn't change anything, it's not power. Maybe your BIOS can't handle the PnP resource allocation to so many cards and stuff ends up conflicting.

Also, to clarify, I not only had stability issues, but multiple times, the computer just would not progress past POST, even though it seems like it's fine. (i.e. the computer does turn on and it beeps as if the POST has succeeded, but the screen stays blank, and nothing progresses. In fact, it beeps quite a bit too soon for the POST to be legitimate.)

That can also be due to conflicts. Again, swap that FX5500 out for a lighter AGP card and see what that does.

I don't want to count my eggs before they hatch, but now it seems to be working, for the moment.

Would dulled or tarnished slot contacts be a factor? I went to a computer repair shop yesterday to get some things:
an S-video out adapter, a DFP [precursor to DVI] cable, the power supply I was going to swap out, and some DeOxit spray.

I sprayed the AGP slot and the PCI slot underneath that, and it seems more stable. I don't seem to get any more problems.

I have had contact problems before, when I had my previous motherboard. A spray of another brand of contact cleaner did the job, until I had to take the video card out. When either the card edge or slot was exposed for some time, it seemed to oxidize enough to where I needed to spray it again.

EDIT: I was wrong.

I did have a Vanta card I bought three weeks ago (It works with all slots filled), and I also have an NV18 (geForce 4, but does not work with all slots filled) and they both seem to confirm the theory that it's the power supply that can't provide enough current.

I did have problems and instability using the NV18 before, but I previously thought the problem laid in the capacitors that I replaced. It wasn't. It works just fine by itself.

Also, while testing, when I reset once before, it got the POST MEMORY COUNT wrong! (My memory is at 640MB. With all slots filled in normal circumstances, that particular fluke error counted around 570 MB or so.)