hello, i'm experiencing issues with my newly built computer shutting down and then constantly attempting to reboot whenever i try to play games (starcraft 2, tf2, and bioshock). it will continuously try to restart until i hold down the power button to shut it off, wait, and then turn it back on. sometimes, it will again shut down if i try to boot it back up too quickly. it has also shut down during several tests such as prime95 and memtest. something that i have found interesting, is when i check my cpu temps using real temp, my 4 cpu cores are running in the low 40's celcius, but the cpu mhz is usually around 1200 mhz and the cpu multiplier is usually around 130x10. these numbers fluctuate (have reached up to 2000 mhz etc.), but mostly stay at the lower level. wondering if anybody out there can help me figure this out. the computer runs everything but games perfectly. here are my specs. thanks.
motherboard: gigabyte p55a ud4p
cpu: intel i5 750
memory: ripjaw 4gb (2x2) 1333 mhz
hard drive: caviar black 1 tb
gpu: sapphire 5770
power supply: gx 650w