Thought I would post an update as I got around to trying out the Compaq (P3) system more. It's got the 440BX chipset so I figured it would take AGP 4x cards. Well, none of them work in it. I've tried a number of cards in it and only AGP 2x cards work. I've had some issues with the ESS sound. I'm not getting any MIDI music in games just sound effects, though that might just be because I was running said games under windows. I put in an SB16 and the sound and music works fine though. I was just hoping to be able to use the ESS sound. The other odd thing is that I disabled the ESS sound in the BIOS and it didn't seem to do anything.

I'll also be doing a thorough cleaning of the other system soon, so I'll be adding more pics of it soon. Need some nice pics of the K6-2 and IBM mobo 😜

Which cards did you try? I'm surprised as the GF4 Ti4600 is concerned the "best" safe bet for BX motherboards.
Not that I'm doubting you, it could be an early revision board or some strange Compaq thing.

The AGP 4x cards that didn't work in the Compaq did work in my IBM intellistation (6889) which has the 440BX chipset (pretty sure its the BX anyways, I haven't pulled the heatsink to confirm). I'll see if I can find a BIOS update. I'll try a few cards again though and see if I can get any to work.

Ok, I tried a few cards and I did get some interesting results.

The cards that did not work:
TNT2 M64 16MB (don't know board maker)
MSI Geforce2 Pro
Radeon 8500
Matrox G450
Matrox Parhelia

Cards that did work:
ATI Rage pro
Matrox G200
STB Permedia 2
Intel i740
Matrox G400max

Cards I did not try:
Radeon 9700pro (doesn't have a heatsink atm)
Radeon x800pro (AGP 8x)
Matrox Parhelia 256MB (AGP 8x)
MSI Geforce4

The reason I didn't try the Geforce4 is because it says it's AGP 8x on the chip. It is keyed for 4x though, should I try it anyway?
The interesting thing is that the G400Max works. So that is one AGP 4x card that works so far.

I updated the BIOS today and now the Geforce 2 card works. I'll try the other cards later but I think it's fixed.

I took a new pic of the Compaq, got some nice beige drive bay covers on it. https://imgur.com/a/B045ai9

I also cleaned out the AMD system and got some pics. https://imgur.com/a/IXnIfIo