My problem. I upgraded the mobo, CPU and RAM on my system and since then I've had problems with 3D games (Asherson's Call and Anarchy Online) and 3D Benchmark. I'm not overclocking anything. The games will either freeze up or my system will just reboot. This happens anywhere from 1 to 30 minutes into the game. 3D benchmark just kicks out to the desktop, but not all the time.
I've loaded all the latest drivers for the graphics card, the VIA chipset and the Win 2000 AGP patch for AMD. I've tried a different Geforce 4 Ti 4600 card, reloaded the OS, disabled the sound and still the problem persists. I haven't tried to flash the BIOS yet, but I don't see a fix for my problem in the update descriptions.
I'd look at the AGP Aperture Size in BIOS. Here more is not better all of the time. I'd set it @ 64 & see if that doesn't help. I use SiSoft Sandra Performance Wizard to tell me if my aperture size is to big & hogging the AGP buss. I'm also running the TI4600 @ 64 on AGP size.
It also could be the DX9. I've heard good & bad about it around here. Being as I've never ran it & don't see why in the near future, I can't tell you about it's problem or lack of problems. You can do a search on DX9 here & see if some of what you read there helps.
I'm still learning & having fun doing it!! Trouble comes with the things you forget or overlook along the way that make it not so fun!!