OK that's... interesting! I have no clue what's the problem, I'm going to just mention what I'd try next if I was facing the same:

Run memtest, change RAM, temporarily remove all not absolutely necessary cards (network, sound), boot clean in pure DOS, and since this board has an uncommon particularity with Voodoo3 also try a different VGA. These are all attempts to narrow down possible culprits, not a final solution.

^ This, but before that I'd spend a few minutes testing with more software that's trying to do more or less the same things, i.e. other versions of Doom 2, different games on the same engine (Doom 1, Heretic, Strife).

Are you running the game from within Win98? What if you run the game from pure DOS mode?

I’ve read somewhere that xmp extreme memory profile can cause faults and shuts down computer no warning. Could be something that doom 2 taps into that nothing else does
Might be worth looking into.

I would second what @konc suggested.

Also, could we have more details on what is the "modern PSU" the system was tested with (and its replacement for the test)? Brand and model would be great, but a picture of it even better.

Being a Pentium III system, it sure isn't going to be that heavy on any of the power rails of the PSU - even the 5V rail, where the CPU gets power from. But nevertheless, I've seen enough old and modern no-name PSUs "loose it" at certain loads and drop out for no reason. It's typically the "gutless wonders" that tend to do this more than any other kind, but not always.

konc wrote on 2024-02-23, 08:18:

OK that's... interesting! I have no clue what's the problem, I'm going to just mention what I'd try next if I was facing the same:

Run memtest, change RAM, temporarily remove all not absolutely necessary cards (network, sound), boot clean in pure DOS, and since this board has an uncommon particularity with Voodoo3 also try a different VGA. These are all attempts to narrow down possible culprits, not a final solution.

Thanks for the idea. I'll give this a try. I don't think it's the Voodoo because it's run 3dMark for 8 hours but I'll swap it out anyway.

elszgensa wrote on 2024-02-23, 08:36:

^ This, but before that I'd spend a few minutes testing with more software that's trying to do more or less the same things, i.e. other versions of Doom 2, different games on the same engine (Doom 1, Heretic, Strife).

I'll give those other games a try

Greywolf1 wrote on 2024-02-23, 08:49:

I’ve read somewhere that xmp extreme memory profile can cause faults and shuts down computer no warning. Could be something that doom 2 taps into that nothing else does
Might be worth looking into.

Is that something that is configured in the BIOS or Windows 98?

momaka wrote on 2024-02-23, 21:19:

I would second what @konc suggested.

Also, could we have more details on what is the "modern PSU" the system was tested with (and its replacement for the test)? Brand and model would be great, but a picture of it even better.

Being a Pentium III system, it sure isn't going to be that heavy on any of the power rails of the PSU - even the 5V rail, where the CPU gets power from. But nevertheless, I've seen enough old and modern no-name PSUs "loose it" at certain loads and drop out for no reason. It's typically the "gutless wonders" that tend to do this more than any other kind, but not always.

Here are the 2 PSU's that have been used. I wouldn't call them generic rubbish but they not the best either.

https://www.thermaltake.com.au/litepower-550w-230v.html
https://www.silverstonetek.com/en/product/inf … es/ST40F-ES230/

Ok so little update. Ran Doom 2 again this morning and it crashed after 3 minutes. Ran it again and it hasn't crashed yet (been running 30 minutes so far). So it appears it's a bit random which is going to make it extremely difficult to find the root cause if I'm swapping hardware in and out. What's strange is Windows doesn't even detect the system power off. When the computer boots up again, you would expect scandisk to start running but it just boots right back into Windows like nothing happened.

I thought I'd also mention this. The BX2000 PC speaker goes off like an ambulance (siren) so I have it permanently disconnected. I believe the reason why it does that it because it cannot detect -5 volts. There is no way to ignore the -5v rail in the BIOS.

I suspect no one else has come across this issue because they are running old PSU's with -5v with this motherboard. See the motherboard voltages in the screenshot below.

Seeing how that CPU is rated at just 26W I doubt it's the simultaneous fault of the two decent looking PSUs. Are your board's caps alright? Maybe the CPU's voltage stabilization is shot.

Which Quake 1 did you use, btw? GLQuake offloads to the GPU, just like 3dmark and Q3. D2 is the one CPU heavy title... well, sorta. It shouldn't make a PIII break a sweat... on average, but maybe it occasionally causes enough of a transient load spike to be an issue? Then again I'd expect those to happen with most any game, but you never know, maybe you got lucky with your choices. Try DOS- or WinQuake if you haven't, at some high resolution. Also Prime95.

> no way to ignore the -5v rail

Voltage Blaster or a DIY alternative.

Ran Memtest86 for 1 hour, no issues

elszgensa wrote on 2024-02-23, 23:43:

Voltage Blaster or a DIY alternative.

Thanks for the idea. I had a couple of Voltage Blaster Mini's sitting around so I built one up and installed it in the BX2000. -5v now showing in the BIOS and the PC speaker isn't going crazy anymore.

I played Doom 2 for 1 hour and no shutdowns. I wonder if the alert in the BIOS constantly going off might have been causing some issue over time? It's a long shot but it's my only guess at the moment 🤣

I'm not taking this has a win yet because it seems to be a bit random but Doom has never lasted this long before. I'll keep testing over the next couple of days.

So that didn't last long.

I managed to grab ABit AB-BE6 off eBay being sold as "for repair". The motherboard ended up being in perfect condition, no issues at all or bad caps. Just needed a BIOS update (it was on the original factory BIOS).

Going to swap the BX2000 with the BE6. If Doom stops powering off the machine then it's either the BX2000 motherboard (re-cap needed?) or the incompatible between the BX2000 and Voodoo 3. I could just swap the Voodoo 3 for another card to test but...I like taking the painful route 🤣