I am looking at a whole new system for under 600 and i was wondering if the Sapphire Radeon HD 6770 has enough power to handle all my games at at least 720p ( Borderlands, Darksiders, Bad Company 2, Metro 2033) . It will be paired with a phenom II x4 955 and 8gb of DDR3 1600. If there is another one for a bit more that would be even worth the money then let me know. Thanks for the help
I would personally suggest skimping a bit on the ram to maybe 4GB and splurging a bit more money to get a motherboard supporting crossfire and an HD 6850. This will allow you to later on being able to add another 6850 increase your performance by large margins.
A 6790 is a little faster due to the 256 bit memory bus, but its not worlds faster or anything. Either card will handle some games fine at 1080P, though the ideal gaming res for a 6770 for sure is something around 1440x900. It will just depend on the game and eye candy settings. You wont be able to do Metro 2033 though maxed out at that 1080p on those cards though. You would have to have at least two 6770 cards running in Crossfire, as Metro is a card crusher. If you really want to know more, you probably should google for HD 6770 and 6790 reviews.
I agree with the above. Drop the RAM down to 4gb, more than that isn't really necessary and you can always add more later. Also drop your versions of Window 7 down to Home from Pro. These things should easily save you enough to get an HD6850 instead on an HD6770. The PSU is also more powerful than you need unless you plan to crossfire. If you don't you could save some money there too.