screen goes grey when overclocking

[method526]

i have a HIS IceQ4 4850 Turbo (stock 650/1000) and i overclocked it to maximum 700/1200 for about a week and my screen started to randomly freeze with a grey screen. then when i click "Auto-Tune", it still does the same thing. so now i'm back at stock. any ideas why this happens? i even have the fan running at 75% speed.

my specs are:
Q6600 @ 3.6 450 x 8
4GB CellShock 800Mhz @ 900Mhz 4-4-4-12
Abit IP35 Pro
HIS IceQ4 4850 Turbo (stock 650/1000)
WD Velociraptor
Antec 1200

 

[method526]

bump any ideas/help?

 

[Cowboy420]

Your card can't handle the overclock..plain and simple. If you need more speed, sell it and get something else.