A possible solution for VIA/AMD users having problems with the 21.xx series drivers...
 
Until last night my PC did not like the 21.xx Detonator drivers from nvidia. They seemed great for OpenGL, giving a nice little performance boost over the 12.90's however D3D seemed very broken - I was getting strange graphical anomalies in GPL, and UT was completely unstable - often freezing or BSOD'ing the system. Also, the system was not capable of getting past 1 or 2 demo loops of 3D Mark 2001. The 12.90 drivers on the other hand were 100% perfect - no problems at all in all games that I play.
 
Then I began wondering "I'm not alone with the above problems, what the hell is wrong with these 21.xx drivers for us VIA/AMD users?"
 
I had a hunch that although Fast Writes and Side-Band Addressing worked fine with the 12.90's I thought perhaps they may have been causing all the problems with the 21.xx drivers on my system.
 
I began to fiddle around with various settings such as AGP rate, Fast Writes and Side-Band Addressing. I was using nvmax to enable/disable FW and SBA, however even with these features 'disabled' in nvmax, H Oda's WCPUID 3.0 (from http://www.h-oda.com) program still reported SBA as Supported/Enabled. I turned off Fast Writes in nvmax and in the BIOS which after a reboot corresponded with WCPUID reporting that Fast-Writes was indeed Not Supported/Disabled. But I was still having problems getting rid of Side Band Addressing (SBA) support.
 
I decided that perhaps nvmax was not instructing the 21.xx drivers properly, so I downloaded and installed the GeForce Tweak utility from found at http://www.guru3d.com
 
I un-installed the 12.90 nvidia drivers and re-installed a fresh set of nvidia's 21.83 drivers from http://www.nvidia.com and rebooted. Surely enough when I got into Windows WCPUID still reported SBA as Supported/Enabled. I ran UT which soon resulted in another system freeze that only the reset button could solve - no joy just yet.
 
Once rebooted again, I used the 'new' GeForce Tweak program and disabled Fast Writes and Side Band Addressing, leaving just the option for 4x AGP for VIA chipsets. I rebooted the system yet again (as the tweak program instructed me a reboot was required) and re-checked WCPUID, finally this time FW and SBA were both Disabled (although SBA was still reported as being Supported - a feature of the graphics card I assume). Well at least I have control over these features again!
 
Since this was the first time I was using the 21.83's at 4x AGP without FW and SBA I began my testing...
 
I ran UT and played it for about 30 minutes - no problems.
I ran GPL - no graphical problems.
I ran a 3D Mark 2001 benchmark - scored 3486, no problems.
I ran Q3A - no problems.
I went back to 3D Mark 2001 and ran a looping demo for 2 hours straight - no problem.
(note - all of these were done one after the other in the order above without rebooting the system!!!!)
 
I rebooted, and again tested GPL, UT and 3D Mark 2001 - no problems.
 
So now my system is happily using the 21.83 WHQL drivers with no problems whatsoever! Have they made a huge difference to performance over the 12.90 drivers? Of course not, but if I had a GeForce 3 they would - and OpenGL is slightly faster according to Q3A timedemo's.
 
Disabling Fast Writes and Side-Band Addressing has definitely fixed all my problems with the 21.xx drivers. I just hope some of you guys with AMD/VIA/nvidia hardware can try what I've suggested and that you are lucky like I was.
 
Just remember that even if you have SBA disabled according to a tweak program, is DOES NOT always mean that SBA is actually disabled!
 
Regards
 
Greggy
 
Athlon 1.33 @ 1.4GHz (10.5x133), Abit KT7A v1.1 4a BIOS, 512Mb PC133 SDRAM @ CAS2, Leadtek GeForce2 GTS 32Mb with Detonator 21.83 drivers (4x AGP, but FW & SBA are both disabled), Creative PCI128, Windows 2000 Pro SP2 with Hotfixes etc, VIA 4in1 drivers ver 4.34 etc ALL 100% stable in 3D!!!!!