Problem with VGA upgrade

[lagrunge]

Hello
the problem i m havisg is this:i just bought a sapphire radeon 6850 to upgrade from my radeon 5770.After installation everything seemed ok and the fist day all run smooth.However when i turned on the pc on the next day i started having blurry spots all over the screen-square shaped and lines- which became more and more while i moved the mouse cursor and finally the system would freeze.i tried many restarts and at times i got a blue screen stating an error concerning the installation of new hardware,but it only appeared for moments so i couldnt note what error it stated Now i m running again on my old vga.Any ideas?the rest of my system: AMD phenom2 X4 965,ASUS Crosshair Formula III,8GB ram ddr3-133,WD 1TB, windows7 64bit,PSU thermaltake 600W

thank you in advance

ps1:when i installed the new one i didnt removed any drivers of the old one.thought there might be compatibility since they r both same manufacturer-company-type.could that be the problem?
ps2:my motherboard supports pci express 2.0 while the new card is 2.1..i think that this isnt an issue right?

 

[clarkjd]

It's always a good idea to remove all old drivers when you install a new vid card. The PCI/E 2.1 card shouldn't have a problem with the 2.0 motherboard.

How old is your PSU?

 

[MKBL]

Sounds like GPU overheating. I would return the card for peace of mind. Even if you sent UPC code for rebate already, you may still return it, as I did for my GTX 460 just the day before the return window would close. The Microcenter in my town refunded me minus the rebate amount.

 

[lagrunge]

PSU is relatively new-1 and a half year when i bought this pc.I guess its condition is good enough still.I ll try out reinstalling after uninstalling old drivers and shal c.thx for the help