256c Gpu

My temp reading for the gpu went up to 256Celsius... it used to be idle at 45-47C. tried reinstalling drivers, tried different ones etc but no change.. my ambient temp is still at 34C... any ideas why the reading is all screwed up?
its a Leadtek 6800GT by the way

 

lol; has to be a bug of sorts, that thing would've been long gone at about 80c. You got the newest drivers? 77.30. Alternativly it mightmean that your core isnt making contact correctly so you may want to put some thermal grease on it. 256c = 493f.

 

i had those drivers but they gave me some other trouble. ive been through basically all the recent drivers and am now using 66.93 which never gave me any trouble but the reading is still at 256C. i am 100% certain that its a software bug just cant figure out how to fix it. strange thing is that the temp alarm isnt going off and that the ambient temp readings are still correct.