Multi colored graphics card problem

[Insanitypays]

I bought an ATI radeon HD 4850 on Newegg last summer.
Everything went smoothly including installation of the most recent drivers...
UNTIL
I started playing Need For Speed Undercover and everything froze, but that wasnt the real issue, what was freaking me out was the deadly rainbow covering my screen. there were green, pink,and blue lines going all over the place on the screen. There was nothing I could do except restart my PC manually. This happens to me in every game, yet only once in BF2. (Ive been playing BF2 on this PC for 3 years) all the other games are from
'09. If it helps, im going to add this little detail in: the one time that my computer went killer rainbow on BF2 (I was playing Project Reality) was on the map Karbala when I was near the mosque.
This is my system:
Operating System
Windows Vista
Motherboard
Board: ASUSTek Computer INC. NARRA 1.01
Processor
AMD Athlon(tm) 64 X2 Dual Core Processor 4200+
Memory:
1022 Megabytes Usable Installed Memory
Video Card
ATI Radeon HD 4850
Sound Card
ATI AA01
Hard Drive(s)
250.06 Gigabytes Usable Hard Drive Capacity
126.22 Gigabytes Hard Drive Free Space
Optical Drive(s)
SM/xD-Picture USB Device [Hard drive]
Power Supply
ASUSTek Computer INC. NARRA 1.01
Monitor(s)
COMPAQ 5500 13.8
Thanks

[TomDackery]

Could it have been your GPU overheated? I know that the default fan settings on the 4850 aren't high enough for keeping the card cool during load. If you haven't, go into the Catalyst Control Center for your GPU card, turn on ATI Overdrive, and set Manual Fan Control (maybe 70%, depends on your preference).

If thats not it, then I'm sure someone else can help.

[Insanitypays]

Couldnt that screw up the card...?
Im going to try it tho, thanks!

[Hitperson]

dead...

my laptop did this and means GPU is dieing/dead pretty much.

[TomDackery]

Couldnt that screw up the card...?
Im going to try it tho, thanks!

If you just change the Fan speed, it should only affect how fast the fan runs.

If it doesn't work, then like Hitperson said, it could be just plain dead.

[HMARS]

Though it's generally not great for the airflow over your internal components, in an overheating tight spot like this you can try opening the case of your tower (assuming this is physically feasible) and see if that helps. You might want to use a temperature data collection program like Speedfan SpeedFan - Access temperature sensor in your computer to see if your computer is in fact running hot.

[Insanitypays]

Okay, im going to try that out