Old motherboards don't work well with late generation PCI cards. I think these cards pull too much power or something. I also encountered problems putting a 8000-series GeForce PCI card in an old system.

Thanks Errius, that may well be the reason. The Zotac manual states 29W of power draw. After some research I found out it is an Intel "Endeavor" board, Intel Advanced/EV https://www.vogonswiki.com/index.php/Intel_Ad … nced%E2%88%95EV

If so, I wonder if there is a way to add power to the GPU, via riser card or such.

No idea. Some of these Zotac 520/610 cards have solder points for a Molex power connector, but not this one.

In 2001 a friend of a friend donated a barebones Socket 7 (Biostar VX chipset motherboard) AT system to me, which was a major upgrade from the 66 MHz 486 that I had. It had a Cyrix CPU, and no video card. I bought a PCI video card from a local retailer. I think it was a Jaton, I cannot recall what GPU but I think it was an Nvidia. It would boot up, but when I went to install the drivers in Windows 98, it refused to work properly. A friend tried it in his P1 system, and he had the same result. These CPUs were too old to work properly with this video card. I returned it, and they sold me a used one megabyte Trident video card which worked perfectly. Chances are there's nothing you can do to get that card to work properly in that system.

@Errius There is a 2 pin header on the board. I cannot find a proper manual that would explain what these do. I will keep digging though.

@Repo Yeah, I knew I was talking chances, but had to try it anyway 😉 Still I wonder what the rechnical reasons are behind the issue. Power is definitely one.

I also have a TNT2 PCI with 16MB on the way to me, we will see.

Thanks.

That 2-pin header is for a fan.

These passive cards run very hot. If this bothers you, you can get a cheap PCIe Zotac card on eBay and swap the HS/HSFs around, connecting the fan to that header.