I have a gigabyte GeForce 8600 GTS which i have had for about 1 1/2 year.
When playing Games (World of warcraft and Tabula Rasa and sometimes TF2) it sometimes freezes and displays wierd colours and faded menu boxes where a menu might have been. Lie this pic i found on the net http://www.teamfortress2fort.com/custom/24/images/galle...
reinstalled latest drivers and directx. Ran aquamark3 and it kept freezing when running test.Had a look inside the pc and removed and reconnected found card to be really hot almost couldn't touch it.
idle temp was about 55c running games about 70-75
put a fan by the video card and this lowered the temp to 45-55 and most games ran better but some still crashed.
TIme for a new Card? or could it be more then just a video card issue?
Maybe take the card out and examine it real closely look for/smell any burned parts especially the little black boxes [ferrite/iron cores,usually only two connections to the mobo] if all looks well and card is clean,try renewing the T.I.M [thermal grease] also a card that is starving for power will act weird also,and check the card's fingers [slot connectors for grease etc]..
Then consider either a new card or a failing psu..