Need HELP with 8800GTX OC

Hello i'm having probs with my 8800GTX OC (overclocked is from factory) i'v had this card for about 8months and been running great untill about month ago when playing cod5 and lots of game the pc just restarted didnt think much of it but its doing it now every 20-30mins when playing the game so i updated everythink even the bios scan for virus cleaned the pc up scan for spyware and defraged it and its still doing the same so now i'm thinking it can be 2 things overheating or the psu


Overheating: So i been running speedfan and cheacking the temps of the GPU it sits at 65-68c idel but as soon as i jump on cod5 the temps jump up to 80-90c but as soon as it hits 90c the pc restarts pc is well vented with 4 fans 2 in the front sucking in 1 on the side and 1 on the back blowing out is there any think in the bios that mite be telling it to turn off as soon at it hits 90c?? only problem i got with that is everywhere i read about the card everyone is saying 90c is ok for this card will easy get in the 100sc so i can't see why its restarting the pc.

PSU: I did have a 1000watt psu in the pc for the 8months the card was going good till it stared the restarts i tryed a 550watt psu (spair one) but still doing the same and ppl been saying it might be my psu as if it was overheating you get artifacts and the pc will not just restart. with speedfan now for the power is. both 1000watt and the 550watt are showing the same power in speedfan


Vcore 1.22V
+12V 8.12 <----------------- for any one who knows about that i'v not got a clue with that
AVcc 3.33

just looking the bio and in there its got
Vcore 1.208V
+ 3.30V 3.376V
+5.00V 5.136V
+12.00V 11.616V

is this right and maybe speedfan is not giving me the right reading


Pc Specs

Motherbored
ASRock ConRoe 1333-D667
Pentiem D 3.00ghz <---- not that good i no
4gb ram same sticks 2gb each and tested both on there own both working in each slot
8800GTX OC 768mb
have i missed anythink

the pc just went off when typing this message so its not just when playing games

PLEASE HELP

thanks
hyper02

This is SO in the wrong place, try the Graphic card forum.