My Intel Q965/963 restarts when I use Google Earth or restarts while I command for checking Graphics Performance (Actually it restarts whenever I use anything that involve Graphics)

I'm using Intel Q965/963 with windows 7, 32bit. Whenever I use any program that involve graphics like Google Earth, or checking Graphic performance my system abruptly restarts without giving any warning (This issue was also arose when I install Windows XP SP3). Please help me diagnose the issue, whether it's motherboard or something else (RAM, Hard Disk, Processor all are working good).