Welcome to VOGONS 😊

This is what I would do.

Remove the second RAM stick, remove the hard drive, the floppy, the optical drive, the sound card.

Basically just the motherboard, processor, 1 RAM stick in the slot closest to the socket and the graphics card.

If you have an Intel processor, I would go with that, just in case.

Then see if you can make it POST again.

I'm not familiar with that motherboard, something I always do is go into the BIOS and load the BIOS defaults or performance defaults. Then I disable all the onboard resources I don't need, like serial and printer ports.

Welcome.
Try a different PSU and/or check the caps in that generic one.

PCBONEZ wrote:

Welcome.
Try a different PSU and/or check the caps in that generic one.

Just a point of warning, be careful when opening up PSUs that have been used recently, because due to some components inside the PSU a charge will stay and slowly ebb away (I always wait at least 24 hours before opening up a used PSU) because if you're not careful, you could end up electrocuting yourself.

But PCBONEZ's idea is sound, if it's an older PSU of cheap make, chances are the PSU might already have bad caps even if the PSU has never been used before.

And welcome to Vogons 😀

That is an AT motherboard, right? Those will usually have either a linear regulator or a VRM to provide power for AGP cards, and those are not always beefy enough. Maybe your stress-testing at a higher resolution made the card draw more power than the circuit could provide, and some components got somewhat damaged. Virge cards are more frugal, so perhaps that is why they still work. Anyway, it is just a theory.

IMHO you should confirm that all the cards still POST fine in another machine, then look up how the motherboard provides power to AGP cards.

Btw I remember reading somewhere that the slowest to discharge component on PSUs will usually discharge completly in minutes. CRTs are where the danger is at.

Wow, you guys are fast!

I've tried as Phil suggested and disconnected absolutely everything except one RAM chip, the CPU and a Voodoo3; disabled every peripheral I could see in the BIOS and plugged it in via a verified working good brand PSU from another machine. Still the same POST problem unfortunately.

@Alexanrs - This motherboard has both an AT and an ATX power connector, and I am using the ATX one. Now you mention it - I guess I just assumed I only needed one or the other, do I actually need both? Would explain a lot if so! Unfortunately I don't have any other AGP motherboards kicking about I could drop the Voodoo3s into to check them, though I doubt all three would have blown at once. Any idea where I could find out how the motherboard provides AGP power? I have the manual for the board, but it is... rudimentary.

A bit more reading online has revealed some Socket 7 mobos actually had a special "Voodoo" jumper that unlocked extra power. This mobo doesn't seem to have anything like that, though.

Nope, you only need one or the other. This jumper you read about, AFAIK, would only work with an ATX PSU, and would skip the regulator onboard and feed the GPU with 3.3V directly from the ATX connector (the AT connector doesn't provide 3.3V, so any AT motherboard MUST have circuitry to derive it from another rail).

I am sorry to say that my suspects all go to the VOODOO cards.
You say that you bought them all from the same seller for cheap, maybe they all are defective in 3D, at full power I mean.
I don't think it's a RAM issue, since it would give instability to the whole system from the installation step and you say that the S3 runs just fine.
AGP slot even on AT motherboards is able to power any card keyed at 3.3V with no problems at all, and if you say that you change your PSU also, there are really no other options I can think and the Acorp is really a good AT motherboard.

Problem is my lack of other hardware to check the Voodoo3s independently. Though I don't see why all of them would suddenly stop POSTing even if the one I was benchmarking failed from stress - I tested them all before I installed Windows, and all at least POSTed. I've inspected all the capacitors on the mobo and graphics cards and they all look good, none blown or bulged - not sure what else to do in regards figuring out if the mobo got damaged.

At this point though I am running out of options for troubleshooting; really the only thing I haven't thoroughly tried is changing various BIOS settings to correct it, it's possible the BIOS just happened to have the "magic" configuration when it arrived that would let the Voodoo3s work, and I reset the CMOS at some point and broke compat. I have been through and tried changing the ones that looked the most graphics related to me though.

Just in case I took photos of my current BIOS settings, maybe some of them might jump out at someone here being particularly dubious looking:
https://dl.dropboxusercontent.com/u/683235/20 … %2015.03.58.jpg
https://dl.dropboxusercontent.com/u/683235/20 … %2015.04.11.jpg
https://dl.dropboxusercontent.com/u/683235/20 … %2015.04.39.jpg
https://dl.dropboxusercontent.com/u/683235/20 … %2015.04.52.jpg

One thing I will try is underclocking the CPU a bit, and see if freeing up any power that way lets the Voodoos start.

Mamba wrote:

I am sorry to say that my suspects all go to the VOODOO cards.
You say that you bought them all from the same seller for cheap, maybe they all are defective in 3D, at full power I mean.

This wouldn't explaing them refusing to POST afterwards, though.

Mamba wrote:

AGP slot even on AT motherboards is able to power any card keyed at 3.3V with no problems at all

Nope, some early AT AGP motherboards cut corners in that regard, and can't deliver all the power the standard dictates. This is a known issue, specially if the motherboard uses a linear regulator. Most motherboards using a buck-down circuit should be fine, though.

I could not see that you tried a different PSU. Do you have another one to try? To me it sounds like a PSU starting to go bad (still can power the weaker S3, but not the hungrier Voodoos).

I tried with a different modern PSU (a modern branded 500 watt one which runs a GTX 970 in its normal machine) and it made no difference.

Well that sucks. I wonder if some invisible electrical damage occurred to the mobo.

The Acorp 5ALI61 is a solid board, heck it even has a ATA66 controller on it, some guys at K6-plus forum back in the days made it work with Geforce3Ti and Geforce4Ti cards with no issues at all, I don't see why he must have problems with a mere Voodoo3.
And if they refuse to post maybe it's because the first was barely able to do some 2D, and the others not even that.
My bet is on the VGA cards, all of them. The mainboard is ok if it works with the S3.
Do same DOS gaming, test it.

Play some early 3D game with that S3, and search for a cheap 3D AGP card (TNT, Radeon 7000 and so on).

The S3 is no real AGP Chip. its just a PCI Chip physical fitted into AGP Slot.

i have one too and it performs worse..
ok you can play turok but incoming gets lot of rendering issues..

When the OP said

In desperation, thinking I'd somehow scuppered my motherboard, I tried the simpler S3 Trio AGP card I had - and POSTed and got into Windows just fine! Strangely the screen through the S3 is slightly washed out and has a very slight flicker to it, but it's a cheap old card so might just be like that.

I wondered if there was damage to the mobo/AGP subsystem based on the S3's behavior. It may indeed just be "a cheap old card", but it does make me wonder.

I would push the S3 as much as possible. Stress it with benchmarks and see if it holds up or not. Maybe it's not drawing enough power from the AGP slot as the Voodoos so the system is not behaving as it does with the Voodoos.

No I don't think so,
2D quality of the Voodoo3 is really high, it's more likely he saw a huge differences between the two.
I agree S3 3D is really bad, but it can prove the signaling of AGP slot is ok.
Anyway, the only thing it can be done here is to test a functional 3D AGP card, even a TNT could be enough.

Mamba wrote:

The Acorp 5ALI61 is a solid board, heck it even has a ATA66 controller on it, some guys at K6-plus forum back in the days made it work with Geforce3Ti and Geforce4Ti cards with no issues at all, I don't see why he must have problems with a mere Voodoo3.

Don't overestimate how much power GeForce3/4 Ti draws in such a system. In an AT SS7 system the card would be HEAVILY bottlenecked by the CPU, and therefore not working at its full capacity. Even the Voodoo3 faster than an SS7 system can really take advantage off, which is why things only went BOOM when the OP increased the resolution. Also, remember, these boards are old now, their passive circuitry (like caps) aged and they probably can't take the same amount of abuse they could when new.

If this is a power issue, though, and assuming the humble S3 works because either it draws too little power (or maybe the chip even draws power from the 5V rail), something like a cheap GeForce2/4 MX should have issues as well. If you have one of those as a spare, test the board with it.

alexanrs wrote:

Mamba wrote:

The Acorp 5ALI61 is a solid board, heck it even has a ATA66 controller on it, some guys at K6-plus forum back in the days made it work with Geforce3Ti and Geforce4Ti cards with no issues at all, I don't see why he must have problems with a mere Voodoo3.

Don't overestimate how much power GeForce3/4 Ti draws in such a system. In an AT SS7 system the card would be HEAVILY bottlenecked by the CPU, and therefore not working at its full capacity. Even the Voodoo3 faster than an SS7 system can really take advantage off, which is why things only went BOOM when the OP increased the resolution. Also, remember, these boards are old now, their passive circuitry (like caps) aged and they probably can't take the same amount of abuse they could when new.

If this is a power issue, though, and assuming the humble S3 works because either it draws too little power (or maybe the chip even draws power from the 5V rail), something like a cheap GeForce2/4 MX should have issues as well. If you have one of those as a spare, test the board with it.

I agree with you, I am not saying that he has to put a Ti card (that's what I would do 😊, I use a FX5900 on mine SS7).
I am suggesting to try another 3D card, even a TNT or Radeon or any 3D GPU AGP 3.3V he can test.
If they works, the voodoo cards are not 100% functional.

The board was working fine then suddenly has a problem with 4 different video cards (with beep codes for it) and possibly RAM problems.
The Vcc for the AGP slot is 3.3v but that may or may not be provided by 5v via a DC-DC step-down regulator.
The situation is similar for RAM slots and the RAM behavior is also suspected by the OP.

When 5 parts suddenly have issues it suggests a power problem and most power problems on old gear are caps related.
I assumed the OP would see bloated caps on the board so I suggested the PSU being at fault.
I have since found a photo of this board showing bloated caps. Will attach pics. See flagged caps in pic 2.

The thing about bloated caps.
- Bloated caps tell you for sure they are bad.
- Unbloated caps do not tell you the caps are good.
Only about 1/2 of bad caps show any visible signs.

Now that two PSUs have been tried the motherboard caps are the prime suspect.

As to checking the PSU caps. I was just suggesting he take a peek in there for any obvious caps problems.
I wasn't suggesting working on it.

On power/danger in PSUs.
A properly designed PSU without any faults will have discharge paths for the caps so they shouldn't hold power for more than a minute or two once AC power is removed. Longer than it takes to disconnect it and get the cover off.
That said, not all PSUs are properly designed and some have faults so it is possible for the caps to still be charged.
The other danger is when AC power is applied there are voltages present inside that are much higher than the AC line voltage. Talking near 400 volts in some PSUs. In at least some designs (probably all) that higher voltage is present on some of the larger heatsinks.
The heatsinks are often energized with one voltage or another so stay clear of them when you have power to it.

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