I'm reluctant to recycle or just throw away dead, but rare stuff. It may come in handy to repair another identical dead board.

My P3C-E has only worked with PC600 RAM.
Probably not the real cause, but might be worth a try.

Not an expert, but did you try it with a different power supply? I had a motherboard that would not post any code till I changed the power supply, even though the power supply worked perfectly fine with a different motherboard. The only clue was that the "permanent reset" LED was lit on the post card.

Yeah I'm of the same school of thought as The Serpent Rider here.
But those symptoms can be caused by many things... so it kinda depends on your expertise and how much time and effort you want to invest to something that ultimately may amount to zilch...
At the risk of sounding like mr.parrot rather than mr.cat, have you taken a look at the caps?

Aside from that, maybe you can check the voltages?
And if you post high-res pics here, some ppl seem to be very good at spotting problems...

did you install CRIMMs in the remaining ram slots? pretty sure you need them. All rdram is not the same as well you must have compatible type of ram as well as crimms or it wont work.

enaiel wrote on 2021-06-22, 20:37:

Not an expert, but did you try it with a different power supply? I had a motherboard that would not post any code till I changed the power supply, even though the power supply worked perfectly fine with a different motherboard. The only clue was that the "permanent reset" LED was lit on the post card.

I have tried two PSUs, one brand new cheap Chinese ATX PSU that whilst it seems to work fine, I'm not 100% trusting of it, it just doesn't have much weight to it. Possibly under powered on the 5v rail. I then tried an XFX 750W jobbie that has never failed to run any ATX system I've thrown at it. I'll try an old ATX PSU that's from the era of the board just in case it's being odd with the lack of -5v rail, though I really doubt it!

mr.cat wrote on 2021-06-22, 22:42:

Yeah I'm of the same school of thought as The Serpent Rider here. But those symptoms can be caused by many things... so it kinda […]
Show full quote

Yeah I'm of the same school of thought as The Serpent Rider here.
But those symptoms can be caused by many things... so it kinda depends on your expertise and how much time and effort you want to invest to something that ultimately may amount to zilch...
At the risk of sounding like mr.parrot rather than mr.cat, have you taken a look at the caps?

Aside from that, maybe you can check the voltages?
And if you post high-res pics here, some ppl seem to be very good at spotting problems...

I'll grab some high-res photos later, but the caps all look good, no bulging, no leaking. I'm pretty handy with a soldering iron and my hot-air station, but I've got limited troubleshooting experience of motherboards and PC parts in general. I can fix something obviously/visibly wrong, but very rarely have I fixed anything that's "invisibly" broken. I've got a decent multimeter, logic probe, and bench power supplies, but no access to a scope unfortunately (not that I'd know what I was doing with one!).

Warlord wrote on 2021-06-23, 04:06:

did you install CRIMMs in the remaining ram slots? pretty sure you need them. All rdram is not the same as well you must have compatible type of ram as well as crimms or it wont work.

There are no free slots, the board should take PC800 just fine going from period reviews and compatibility lists. As I say, the RIMMs are known working. I don't own any continuity RIMMS though so can't try a single stick at present. I'm going to get some alternative RIMMs and a CRIMM to try single slots.

This is the board in question:

And here's a link to a Google Photos album for the board with close ups of all areas of the board front and back:

https://photos.app.goo.gl/xrRvNnd5zpt2K1dU8

Checked the voltages and they are all stable (regardless of PSU). The reset LED is constant on the POST test card however, regardless of if there is a CPU/RAM/GPU installed in the board.

No idea what diode mode readings should show for the reset pins, but I only get a reading if I have the +ve lead connected to the ground plane, and the -ve lead connected to the reset header pins. Compared to a working S775 board I have to hand this seems wrong, as both pins read in both directions.

I'm guessing something has shorted, but nothing appears to be getting warm to the touch 🙁

This might be related:
Re: (The Tuala-Bus) Pentium III-S 1.4ghz, AWE64G+ Live, Voodoo4 4500 Rambus rig
Also try booting with a pentium 2

Do you have the tools to check for the presence of clocks on the oscillators?

Schule04 wrote on 2021-06-23, 12:48:

This might be related:
Re: (The Tuala-Bus) Pentium III-S 1.4ghz, AWE64G+ Live, Voodoo4 4500 Rambus rig
Also try booting with a pentium 2

Good find, shame mastergamma12 didn't go into more detail about what "I thought it was dead until I found out that the power cable for the button wasn't in the right location because the system would turn on but not post period" meant in terms of a fix. Would it be bad form to post a reply to that thread when the last activity was 7 months ago?

dataino.it wrote on 2021-06-23, 12:58:

Do you have the tools to check for the presence of clocks on the oscillators?

If I can't check it with a DMM then no, I don't have any oscilloscope or similar.

I think that's honestly a fairly recent post to reply to, compared to some posts on this forum and it's not off topic. So personally I would ask him in there, in your situation. It's a weird description of his problem and 2x strange that it matches your problem.

Seems that the clock generator chip (ICS 9248AF) is getting quite warm very quickly.

Never seen a clockgen chip die/internally short, but it certainly seems likely.