Whats Wrong With My GFX Card [PIC]

Yo Guys. Seriously i am gonna tell the truth and you guys might just already know that problem. I took my ATI Radeon X800 and 1GB of Ram and Inserted it in my Moms HP desktop. [not rly a noob.i know how to install hardware]. I dont know if it matters if there is an ATI in an Intel Machine. I have all the drivers up to date and and DirectX9 installed. As you can see in the pictures, this happenes MOST of the time. Some times if i am lucky i can exit Source and rejoin and somtimes everything seems normal but other times i get random ass spikes on my guns and wierd ***. But the main prob is the wierd checker boards. It even goes on mydesktop so i know its the card some how. Plz help.

Specs on this comp:
2.80ghz
1Gb Ram
Radeon X800
xp SERVICE pack 3

Or you could try this:

http://hardforum.com/showthread.php?t=1421792.

And yes, the technique is call 'reflowing' and is widely used in the electronics industry, albeit in a slightly more controlled fashion.

Okay. Underclock it and play for an hour. If no problem, then it's still useable.