New Computer Problem Please Help

Here is my system:

AMD 64 Fx-51 2.2ghz
1024mb Corsair XMS DDR400 Ram (2 sticks of 512mb)
MSI K8T Master 2Far
Seagate Barracuda 120gb SATA HD
Radeon 9800xt (ATI Retail Version)
Thermaltake PurePower 420watt Power Supply

Windows XP Professional

Here is my problem:
Whenever I try to run a game (CS to test opengl and Warcraft 3 to test d3d)
They freeze after a few minutes and i have to hard reboot. When I play
the games I see really quick flickers of artifacts and it just stops.

Here is what I've tried:
-Tried one ram stick at a time, still froze on each.
-Updated bios
-Installed latest Hyperion drivers (4.51)
-Switched out video card for my old fx5200. Still froze.
-Took out sound card and it still froze.
-DirectX 9.0b
-NOTHING IS OVERCLOCKED
-I have tried a different power chord for the 9800xt, and I have given it
its own power chord to the supply (didnt share it with harddrive)
-Catalyst Drivers 3.9, and 3.8 didnt work either.
-I tried AGP 4x and 8x and ive had the aperture at 64, 128, and 256

I recently recieved this error message one time. Never happened during the other
crashes but here it is: Machine_Check_exception
Error Code was: 0x0000009c

PLEASE HELP ME!!! I AM OUT OF IDEAS.

I can't find any situations similar to mine. My current timings according to CPU Z are: 200.5 mhz, 2-3-2-6 then bank cycle time is 11 and DRAM idle timer is 16. As you probably know the fx-51 has 800mhz fsb so what should i do with the ram or where on the forums that you linked me to should i be looking? Sorry to bug you again

Have you checked your CPU temp? Most BIOS's will give you a temp reading - over 50c starts to be a concern.

Here's something I googled up: <A HREF="http://support.microsoft.com/?kbid=329284" target="_new">http://support.microsoft.com/?kbid=329284</A>

Common reasons for this error message:
1. Overclocking. You have'nt. So this is eliminated unless faulty cpu.
2. Bad Ram? Have you ran memtest?
3. Overheating. What are your temps? Check that all fans are functioning
4. Bad power supply. Check your rails, or try another to see if that's it

Good Luck

XP 2000+
MSI KT3 ULTRA-2 KT333
Maxtor 60GB ATA 133 7200RPM
512MB PC2700
ABIT G4 Ti4200 OTES 64MB
Win98SE

I tried running everything with my nvidia fx 5200 (requires no extra power and runs on little power) and it still freezes. are you talking about the agp voltage or what?