Well I finally figured out why my X1900 XT was idling at 70 deg and would artifact after 10 minutes of gamneplay-- stupid me forgot to remove the metal piece on the case blocking the fan exhaust.. it never occured to me because Ii was replacing a 7800 GT with an internal fan. Needless to say my idle temps are 20 deg C lower and I have no problems.. hopefully noone else is as stupid as I am, but if so maybe this will help.