Yes there is a setting in the cmos for selecting either PCI or ISA as primary during start up.

Cheers,

Also make sure that your video card is not too new. Your board might not have support for PCI 2.2 cards yet (most cards from the late 90s onwards, including the Geforce).

asdf53 wrote on 2022-08-06, 21:49:

Also make sure that your video card is not too new. Your board might not have support for PCI 2.2 cards yet (most cards from the late 90s onwards, including the Geforce).

Specifically, it's a voltage thing. PCI cards with universal keying should be backwards compatible with 5V-only PCI slits - but not all are, particularly not later cards. It's possible to mod most boards to supply the required 3.3V for these cards - but a far more obvious solution is just to use a more period-correct PCI card (with PC-compatible VGA BIOS). Anything from before 2000 will work fine.

I can definitely confirm SiS 501/2/3 chipset supports PCI VGA as a primary source - my first own PC was a P60 on an MSI motherboard with SiS 501 chipset bought in January 1995, together with an S3 868 PCI VGA card. It worked "perfectly" (as perfectly as an el-cheapo S3 card with washed-out analog circuitry would ever work when paired with an abominable low-end 14" monitor) until I finally was able to upgrade to a Celeron 366 with TNT2-M64 in late 1999.

I suspected the PCI version might be the issue. Looking more closely at the slots, I see they're absent the compatibility notch on the front of each PCI connector.

I'll round up a pre-2000 PCI video card as it definitely sounds like a PCI support/implementation/compatibility problem.

Thanks all for the advice!

dionb wrote on 2022-08-06, 22:10:

asdf53 wrote on 2022-08-06, 21:49:

Also make sure that your video card is not too new. Your board might not have support for PCI 2.2 cards yet (most cards from the late 90s onwards, including the Geforce).

Specifically, it's a voltage thing. PCI cards with universal keying should be backwards compatible with 5V-only PCI slits - but not all are, particularly not later cards. It's possible to mod most boards to supply the required 3.3V for these cards - but a far more obvious solution is just to use a more period-correct PCI card (with PC-compatible VGA BIOS). Anything from before 2000 will work fine.

I can definitely confirm SiS 501/2/3 chipset supports PCI VGA as a primary source - my first own PC was a P60 on an MSI motherboard with SiS 501 chipset bought in January 1995, together with an S3 868 PCI VGA card. It worked "perfectly" (as perfectly as an el-cheapo S3 card with washed-out analog circuitry would ever work when paired with an abominable low-end 14" monitor) until I finally was able to upgrade to a Celeron 366 with TNT2-M64 in late 1999.

mklz wrote on 2022-08-06, 21:27:

...
2. The BIOS successfully launches the option ROM for my PCI Adaptec SCSI card, so maybe a ROM BIOS edit can initialize PCI video as primary? (I have the tools to wipe and program ROMs)
...

No, the initialisation of option ROMs is very different from the initialisation of primary display adapters.

The initialisation of the primary display adapter is done very early in the BIOS routines; basically after the first tests in the BIOS, like a very small amount of RAM (like 64 K).
The option ROMs are initialized after full RAM initialization and you basically can see their outputs on the primary display.

The ROM of the primary video adapter resides at segment C000.
Option ROMs can be placed after the video ROM; somewhere between D000 and EFFF; perhaps between C800 and F7FF. However, the BIOS will scan the address space behind the video ROM for option ROMs and jump into them.

I rounded up a Matrox MGA-2164W, and it POSTS and plays well. Right on!

mklz wrote on 2022-08-06, 23:29:

I suspected the PCI version might be the issue. Looking more closely at the slots, I see they're absent the compatibility notch […]
Show full quote

I suspected the PCI version might be the issue. Looking more closely at the slots, I see they're absent the compatibility notch on the front of each PCI connector.

I'll round up a pre-2000 PCI video card as it definitely sounds like a PCI support/implementation/compatibility problem.

Thanks all for the advice!

dionb wrote on 2022-08-06, 22:10:

asdf53 wrote on 2022-08-06, 21:49:

Also make sure that your video card is not too new. Your board might not have support for PCI 2.2 cards yet (most cards from the late 90s onwards, including the Geforce).

Specifically, it's a voltage thing. PCI cards with universal keying should be backwards compatible with 5V-only PCI slits - but not all are, particularly not later cards. It's possible to mod most boards to supply the required 3.3V for these cards - but a far more obvious solution is just to use a more period-correct PCI card (with PC-compatible VGA BIOS). Anything from before 2000 will work fine.

I can definitely confirm SiS 501/2/3 chipset supports PCI VGA as a primary source - my first own PC was a P60 on an MSI motherboard with SiS 501 chipset bought in January 1995, together with an S3 868 PCI VGA card. It worked "perfectly" (as perfectly as an el-cheapo S3 card with washed-out analog circuitry would ever work when paired with an abominable low-end 14" monitor) until I finally was able to upgrade to a Celeron 366 with TNT2-M64 in late 1999.