My computer wont shut off when it is just running the internet or some small program but it shuts off almost instantly when i play a game. I have a 750 watt power supply. I just got a new motherboard. I run sli with two 9800gtx+ I have a extreme tuner and have been watching the temp it doesn't appear to ever go over 60. I just put in a brand new cpu fan and another 120mm fan in the back. I don't know whats wrong plz help.