everytime i start up my computer it works fine for about 5 minutes and in that time, im actual able to play some games and stuff but then my screen freezes and then turns white. is there something wrong with me GPU?? my system specs are: intel quad core q6600 2.4ghz Crucial 4gb ddr2 800 ram diamond ATI 4670 1gb ddr3 ive never had this problem before and ive only recentiy started encountering it today after trying to overclock my gpu by 5mhz. is it possible i did something wrong??