I'm trying to install a nVidia TNT2 M64 (16MB, PCI) into my retro writing/gaming PC, but the motherboard does not seem to be detecting it. A basic run-down on the specs of this writing computer are as follows:

Motherboard: FIC VT-502 (i430VX chipset) -- Flashed to latest available BIOS that I could find (v.1.13FF104, 2/22/1999)
Processor: AMD K6II 266MHz, clocked to 300MHz (my memory could be off on this one. CPU-Z and /proc/cpuinfo both seem to indicate this is a K6-III+)
Memory: 128MB EDO RAM
Hard Drive: 20GB ( 6.4GB - Win2k, 6.4GB - Debian Wheezy, 6.8GB - Debian Home folder, 403MB - swap )
Operating System: Windows 2000 Professional, Debian Wheezy (Jessie dropped the Glint XOrg drivers)
Video Card: 3dLabs Permedia2 8mb (Looking to upgrade this one for reason stated above)
Sound Card: Yamaha PCI Audio (YMF-724)
Monitor: NEC MultiSync LCD1560M

As I've said, I attempted installing the card into the system, and I'm greeted with a long beep, followed by two short ones, which indicates a VGA problem. The system still boots fine, gets through POST okay, but there's no display. Putting the Permedia2 back in and enabling IRQ for VGA still does not produce any results.

I moved the card into a newer system (ASUS P5PE-VM mainboard), and the card is detected there. I've even upgraded its BIOS to the latest available, but still no joy in the VT-502.

Any ideas on what could possibly be the cause?