Re: GPU Upgrade Questions.
the 670 wants a minimum of a 500 watt power supply, so you should be fine. That being said, the rosewill is a budget minded brand and may not be the best, or perform as much as it is rated for. but, if it has worked for you so far, you should be all set. evga is a fine brand.
Intel Core i5-2500K
ASUS P8Z68-V LE LGA 1155 Intel Z68
1Tb Samsung Spinpoint F3
1Tb WD Caviar Green
2Tb WD Caviar Green
8gb DDR3 Corsair Vengeance 1600
Sapphire Radeon 6870