Nvidia 295 pc shuting down, need help

Hello everyone, I need some help when I'm playing games like lord of the rings online with settings set to high or ultra high in 1920x1200 or call of duty world at war with high settings. My pc will just shutdown and then few seconds later turn it self back on. I don't think it over heating but im really not sure. Any help would be great . Thanks

PC specs:
CPU: Intel Core i7 920 Nehalem 2.66GHz
CPU Fan: ZALMAN CNPS9900LED
Motherboard: ASUS P6T
Memory: CORSAIR DOMINATOR 6GB (TR3X6G1600C8D)
Video Card: BFG Tech BFGEGTX2951792E GeForce GTX 295
PowerSupply: Thermaltake W0106RU 700W
Soundcard: Creative Sound Blaster X-Fi XtremeGame
HD: Raptor WD1500ADFD 150GB x 2
DVD-ROM x 2
2x 120m Fans
2x 92m Fans
windows 7 64 bit

Well I think I fix my issue, bought a new power supply a thermaltake toughpower 850w which seem to fix my issue of the rebooting. I guess 700w was just not enough for this machine lol.