IRQs aren't an issue with PCI, interrupt lines can be. Solution there is to try different combinations of slots - but you already did that.

You have two pretty notorious pieces of hardware here, the PC Chips motherboard and an el-crappo Silicon Image controller. It's almost certainly going to be one or the other causing the problems. Do you have any other similarly-aged boards you could try the combination with?

The problem with SI is that it assumes a more modern system (and PCI version) than you have here. Offhand I'd say that's the most likely cause. It would probably work fine with a more period Promise/Highpoint-based controller. But if you only have the controller for large drive support, you could try a different approach: do you have a network card with an (E)EPROM socket? If so you could flash an XTIDE universal BIOS onto one, stick that in the NIC and let that handle drive detection using only the native onboard IDE.

I searched thoughout my old pc cards collection and the candidates are:
- PCI 3Com 3C905-TX (Bomerang), comes with a DIP32 Atmel AT29C512 512K flash chip (says its 5V only) (didnt show anything at boot)
- PCI 3Com 3C905B-TXNM (Cyclone), comes with a DIP32 socket, no chip, network detected but doesnt connect
- PCI Realtek RTL8139D, DIP28 socket
- ISA Wondbond MDA + DB25 card, socket DIP28

I've been reading the XTIDE docs and it says i need a 16kb chip or larger, though im not sure if that flash chip is fully compatible with an eeprom. i dont have experience with external memory chips though i also found a Lo-Tech ISA ROM card which uses a 1Mbtis flash chip so i guess it should work. Otherwise i have plenty of dead motherboards, im sure theres some chips i could use from them. Otherwise shoot me the part number and ill buy the chip.
Any other advice is welcomed. I dont a programmer so i guess ill have to rig one up.

I had a similar issue except in reverse, the RAID card BIOS was not recognized. Cause was motherboard BIOS not liking Video BIOS that was more than 32KB in size, it failed to allocate space for RAID BIOS due to it, different video card with 32KB sized video BIOS fixed the issue for me on that board (I no longer remember exactly what it was, but also a socket7 board).

Sadly this Silicon Image card has an OTP chip. I have got a socket and a flash chip thats compatible with the Sil680A chip and big enough to flash a bios thats only the IDE controler (no raid) but i dont have a smd station and my attemps with dead boards with a regulable heatgun have been barely successful, so i kind of dont feel too confident about removing the original rom and repleacing it with a socket..... 😒

Edit:
- Tried installing the raid card in a slot before the video card and same result.
- Tried the 3com card with the flash chip and also got no video. Same result removing the flash chip.

The 3com card has a tiny serial flash chip besides the big removable flash chip. Its a 1K serial eeprom.
The Stealth II has a AT29LV010A-20JC 128K 3V flash chip.
One of the PCI cards recomended at M571.com has a 64k bios.

So i guess it most likely is something like what happened to Tiido. Ill see if i can find a pci card with a small vbios. Maybe 64k solvs the problem.

Edit2:
So i tried a few other network cards. The video card wont work with anything else installed. Its not just the raid card, anything else causes the video card not to boot.

The inofficial K6-2+/III+ BIOS avaliable at http://web.inter.nl.net/hcc/J.Steunebrink/k6plus.htm (make sure to pick the one corresponding to your Rev. Nr.) includes an updated VGA ROM. Have you tried this?

Doornkaat wrote:

The inofficial K6-2+/III+ BIOS avaliable at http://web.inter.nl.net/hcc/J.Steunebrink/k6plus.htm (make sure to pick the one corresponding to your Rev. Nr.) includes an updated VGA ROM. Have you tried this?

Just flashed it, still doesnt detect the 80GB HDD (doesnt say it was patched for that so i guess it was expected), still wont detect video card with anything else present. The only good from this is now i dont need the bios patch in autoexect.bat