Does it work again after leaving it off for an hour? I had a problem with some memory that would get through one pass of memtest86+, but then start to give errors at random addresses, but the errors were always in the first few bits, which turned out to be the actual chips near the top of the stick, which were in a corner of the case without much airflow, and right next to the motherboards 12V -> 3.3V regulator. I pointed a fan at the general area and the problem went away.

That said, formatting floppies doesn't stress anything, so it probably isn't a heat problem. What RAM do you have in there at the moment? If you've got more than one stick, can you test them one at a time?

snufkin wrote on 2021-05-08, 21:36:

Does it work again after leaving it off for an hour? I had a problem with some memory that would get through one pass of memtest86+, but then start to give errors at random addresses, but the errors were always in the first few bits, which turned out to be the actual chips near the top of the stick, which were in a corner of the case without much airflow, and right next to the motherboards 12V -> 3.3V regulator. I pointed a fan at the general area and the problem went away.

That said, formatting floppies doesn't stress anything, so it probably isn't a heat problem. What RAM do you have in there at the moment? If you've got more than one stick, can you test them one at a time?

I left it off for about an hour and a half. I just turned it on, and the power light blinks continuously, no more beep codes, monitor doesn't engage. I held the power button and it wouldn't shut off, and the reset button won't reset. I had to unplug the power cord. When I plugged it back in, the PC automatically turned back on and it was the same with the blinking power LED and I had to unplug the PC. I have no idea what is happening. I don't think it is the Voodoo 5 (at least I hope like hell it isn't,) because when it was rebooting the first time, the monitor was engaging and I could read the screen until it rebooted again.

I don't have any other PC100 RAM sticks to test, so I am going to order some from ebay. The one I have is a single 128mb stick. I am open to ideas, and I hope it is easily solvable because I have put a lot of time and money into this build and it is important to me to get this working. Barring any ideas that anyone may have, and until I can get some RAM sticks, I am probably going to disassemble everything but the RAM, V5, and the main SSD and see if it boots. The machine currently has:

1. a DVD drive
2. CDRW drive
3. 128GB SSD
4. CF-IDE adapter/drive
5. 3.5 floppy
6. 5.25 floppy
7. 128mb RAM stick
8. Voodoo 5 AGP
9. Voodoo2 (with plans for a 2nd one for SLI)
10. Typhoon Voodoo 4mb
11. Sound Blaster Live!
12. Live! Drive
13. Sound Blaster AWE32
14. Antec 350 PSU

Unplug everything apart from RAM and a *basic* video card and try again. A 350w PSU for all that? You're really pushing it IMO.

How's your bios battery? I've had a few boards do this exact thing when the batteries are low or dead/missing

There are many things that could cause what you're experiencing. Get a Multimeter and test the voltages of the PSU, with and without any load.

The PSU is brand new. I took out everything and swapped the Voodoo 5 out with a different AGP card and I also tried a PCI video card. It is still powering on, no post, blinking power LED. Maybe the mobo died. I may try the cmos battery (have to take one from another mobo) though it should still post with a dead battery and then get a bios settings error, I would think.

megatron-uk wrote on 2021-05-08, 22:47:

Unplug everything apart from RAM and a *basic* video card and try again. A 350w PSU for all that? You're really pushing it IMO.

It is what I have on hand, and I wasn't running anything that would draw a lot of power.

How many amps can this PSU output on +5V line? You have a lot of 5V-heavy stuff here, and there may be some undervoltage situations caused by excessive load, also if capacitors are bad or have gone bad recently, such high load may definitely cause some problems (edit: if PSU is brand new, that shouldn't be a problem, but still may be a problem with mainboard). Definitely a good idea to check voltages with a multimeter.

adalbert wrote on 2021-05-08, 23:31:

How many amps can this PSU output on +5V line? You have a lot of 5V-heavy stuff here, and there may be some undervoltage situations caused by excessive load, also if capacitors are bad or have gone bad recently, such high load may definitely cause some problems (edit: if PSU is brand new, that shouldn't be a problem, but still may be a problem with mainboard). Definitely a good idea to check voltages with a multimeter.

I have a multimeter. I don't have a lot of experience using one, but I can look into it.

I have quite a few motherboards that will not post with a low, dead/missing battery. I've also had motherboards act very weird with low/missing batteries

Turn on the PC, grab one of the Molex connectors and check:
- the Voltage from Black line to Red line, it should be 5V (+/- 0.2V)
- the Voltage from Black line to Yellow line, it should be 12V (+/- 0.2V)
- the Voltage from Black line to Orange line, it should be 3.3V (+/- 0.2V)

If you're out of these ranges, then likely the PSU is the culprit, if you can try another PSU.

Whenever I've had this issue in the past, it's been RAM or PSU. Like someone else said. I had some ram that would only get unstable after being on a while and would pass memory tests.

As adalbert mentioned that is a lot of stuff off a 350watt supply, specially the newer ones which push more +12v than +5v which your board (like an Athlon) and parts require.
As aaronkatrini mentioned check the PSU voltages under load from the board. The +12v and +5v can be checked from any free Molex connector, the 3.3 must be checked at the 20/24pin connection (+3.3 orange wire, any black in ground)
When was the last time you pulled the Heatsink off the CPU and cleaned and re-gooped it (HS compound does dry out)? Also clean the cpu and memory slot edge connector with some Isopropyl alcohol and make sure the fan is working.
P2B is old from late 1990's and if never recapped it easily could be caps failing as mentioned..
added: also try a different memory slot....

IIRC the pre 2005ish Antecs had about 66% of output on 5V, then the Truepower 2.0s came out for the 12V heavy thoroughbred and northwood up era boards, and the hungry 9500s etc, and then it switched 66% to the 12V... so the later Antecs put out half the power on 5V the early 2000s ones did. Back in the day, I'd say ppl were running rigs that spec on "good" 250s or 300s, with 200W on 5V. So if you've got something that says 40A on 5V you should be okay.

Every time power supplies are discussed people will suggest extremely high power requirements on the +5V rail and anytime that happens I just can't help myself:
Please, guys, no Pentium III gaming PC needs 40A on +5V. Pentium III systems often draw less than 100W at the wall. Dual Athlon XP systems will run fine with a contemporary PSU that delivers 35A @+5V.
I agree that with the symptoms he describes OP should check wether his PSU is ok but a decent PSU that will deliver 150W @+5V&+3.3V combined will be more than enough. A typical contemporary PSU would deliver ~250W on all rails combined.

If you carefully touch each chip on your stick of RAM, are the temperatures consistent or do one or two chips get particularly warm?

I reseated the RAM, and the same issue persists: All fans spin up and stay running, including the ones plugged in directly to the mobo. No beep codes, just a blinking power LED and the HD LED lights up and stays on without blinking. So the PC went from rebooting during my floppy format project - to rebooting during the boot sequence - to giving me a 1 long beep every second or so - to no beeps with a blinking LED.

Prior to this, I made a post about how my floppy drives were working one minute and then they weren't working or only reading in DOS (no writes) with the a: drive -but not in Windows, with the b: drive not working at all, to them working after I unplugged everything and plugged them back in differently (changed splitters and rearranged which devices were daisy chained with each other. I had wondered if the floppy controller was beginning to fail.

The PSU, while old, was never used, prior to putting it in this build. I bought a white/beige Antec desktop case for a 486 build (still waiting for the 4DPS Tomato board to come from Russia been a couple of months now,) and the case was in an unopened Antec box (NOS, basically.) I swapped it out because it had an extra floopy-molex connector, meaning I could do away with one of the splitters, as I have 3 devices that require the tiny molex connector.

After I got the floppy drives working, I was able to format 5.25 floppies for hours. I shut it down that night and resumed yesterday, and ran the PC for maybe an hour, when the issue occurred. I am going to try another PSU. If that doesn't work, I am going to assume that the mobo died. I really hope that is not the case, as the P2B is an amazing and famed board. Since I am going to buy different RAM to test, I may just buy a CPU/mobo/RAM combo, as I have been trying to hunt down a slotket that will allow me to put a 1.4GThz Tualatin in this build, to make it the absolute best that it can be. If I order just the RAM and it turns out that the RAM wasn;t the issue, I will then have to lose more time as I go to buy another mobo. If the P2B still works, I think that with the age of these parts and the mental stress of dealing with this, I should have a couple of backup boards on hand.

I intend on setting up an old school computer on an old school desk with accessories and peripherals from the late 80's to 1999, so that I can feeling like I am going back in time as I play the old games, in the way they were meant to be played. I even found a NOS 19" KDS monitor, and the 1st Voodoo 5 I bought wasn'tworking, and the 2nd one does work. Two steps forward, one step back...

So I am going to try different PSU - order combo - test P2B with RAM from combo - remove P2B if it still doesn't work and examine it for bulging caps. I don't know how to recap (not yet - I intend on learning, because of situations like this and because I like learning new skills, and because the V5 seems to need a recapping at some point, from what I have read on here and seen on youtube.)

I honestly think that I don't need to hunt down a bigger PSU. My p3 Gateway with a Voodoo3 and a SB Live! and other components ran on a stock 200W, and the PC will never run all components at the same time.

Doornkaat wrote on 2021-05-09, 13:02:

Please, guys, no Pentium III gaming PC needs 40A on +5V. Pentium III systems often draw less than 100W at the wall.

Sure, I run P3 with GF3 Ti 200 off a pico PSU and 65W 12V brick. But a P3 with 3 graphic cards, 3 sound cards and 6 drives could be pushing it 😁
But a dual Tualatin setup didn't want to run off a PSU with 18A on +5V line, while it ran with 22A. And some modern PSUs often have 20A or less on +5V, which is fine for usual single CPU / single GPU / single HDD setup, but may be too little if you start installing buch of devices in computer. We still don't know the current ratings for OPs PSU.

Anyway, you could also try to check if the CPU gets power, there could be also a problem with broken VRM. You can try measuring the voltage on MOSFETs near the CPU.

I don't believe that testing the NOS PSU will be necessary. I replaced the coin battery, and the symptoms persisted. I grabbed a random PSU that I had lying around, and the PC now boots, much to my ABSOLUTE relief. Now I need to think if the setup somehow killed the NOS PSU, or if the NOS PSU was faulty (it happens.) I wasn't running any 3d games or anything, or using the sound cards to play anything, or running the optical drives - just the Voodoo5 for the display, the SSD as it is where Windows is installed, and the 5.25 floppy to format all of these floppies, one right after the other (I bought a stack of 50, and so far only one has bad sectors, though the bad sectors were reported right before the issue occurred, so I will reformat it to see if it is related.)

I am still going to grab some spare mobo/cpu/ram combos, just in case, while I still search for an available, P2B slotket that will allow me to slap A 1.4Ghz Tualatin in there for the ultimate set up. I also need to solve the network connectivity issue due to a lack of slots, and I am still hoping to find a serial-to-ethernet solution. Though if I can buy an AWE64 legacy, I can remove the SCC-1 that I forgot to mention, and get an ISA NIC and a serial 56k V.92 to complete the set up. I considered a PCMCIA card, since I can swap different cards out depending on need (and I have seen modem/NIC combos,) though IO have read posts on here explaining that it could be difficult to set it up properly and without conflicts, especially in a machine with so many components.

I appreciate everyone's help and suggestions. I know that many modern PSUs aren't good for these old components, so I am looking for recommendations so that I can buy a couple of suitable PSUs for this project. A modern modular PSU would be a bonus. I am so relieved, but this is stressful. It is taking WEEKS to put this together without issues. I want to be able to sit down and play some old school classics, especially since, with a few exceptions, the majority of modern games are garbage, in my opinion.

I'd open the old PSU and see if any of the caps have leaked. But glad to hear the system is running again.