Hello and welcome to TSF
first of all your PSU is not high quality enough to handle your video card
you need this:
Corsair 650 W, 100$, 90$ after rebate :
http://www.newegg.com/Product/Produc...=Corsair%20650
your video card temps are a bit high
download RivaTuner from my sig and try to adjust your Fan control and set it to 100%