I put a new K6-2 450 in my system (Voodoo3 2000 @160mhz, 96MB PC-66, VA-503+, CL PCI128) and had some similar problems with in Descent 3 and had system instabilities (mostly in 3D games). I clocked my cpu to 400 and it fixed all the problems. So I did what over clockers do, I bumped the voltage up to 2.3v. Runs perfectly stable now.
Descent at 800x600 48fps
Q2 demo1 at 1024x768 74fps
Q3 with texture 3, 16bit, high sound, Dynamic lighting, high sky, and low geomitry at 1024x768 41fps.
UT is limited by the number of opponents more than the graphics settings. 2=48, 4=40, 6=35, 8=32, 16=24 at 1024x768, 16 bit, high texture and skinsand detail textures.
AMD Phenom II x4 945 3Ghz | ASUS M4A77TD | 2X WD 1TB SATA 2 hard drive | 2x2GB Corsair XMS3 | nVidia GeForce 8800 GTS | ATI TV Wonder Theater Pro 550 | Antec P-160 case | Antec 650w Earth Watts | LG Blu-ray Super Drive | LG DVD RW | Windows 7 Pro