I'm overclocking my Sapphire x850XT (520/540) stock currently, and I got a small artifact at 570mhz Core and backed it down to (560/600) and I am currently stress testing the video card. The core temp is hitting stable temps at about 69-72c. Is this too high? What is the best temp for a video card to max out at while gaming? I don't want this card to be at a huge risk of alot of decrease in the life of the card, and if I have to lower the mhz of the core/mem to have a smarter max temp, I will do so. Input please? Thanks.