Re: GTX 280 and Rosewill 850W
If you have a PCI-Express compliant motherboard, you may be able to get away with the 6-pin to 8-pin adapter. PCI-E 2.0 slots give 150W of juice to the card instead of 75W. That would help. My motherboard is not PCI-E 2.0, but I still seem to be O.K. I have a 750W power supply.
Core i7 2600 @ 3.7GHz
EVGA GeForce GTX 780 Superclocked 941 MHz
1TB Seagate HDD 7200 RPM 32MB Cache
16X BluRay-RW drive
Dell 30-inch U3014 monitor