APPROXIMATE PURCHASE DATE: (e.g.: this week (the closer the better)) Around $400
USAGE FROM MOST TO LEAST IMPORTANT: Gaming(Starcraft 2, Bad Company 2, Bioshock 2, and Etc), Browsing, Movies.
CURRENT GPU AND POWER SUPPLY: 750 Corsair PSU
OTHER RELEVANT SYSTEM SPECS: Motherboard would be ASUS P7P55 LX LGA 1156 Intel P55 ATX Intel Motherboard, 4 Gb of RAM, Intel core I5 750 CPU @ 3.8 GHZ, Right now I'm using a 5770 but Long story short I have to sell it in another system that I've built.
PREFERRED WEBSITE(S) FOR PARTS: Newegg
PARTS PREFERENCES: I wanted to get two HD 6850 Cards but I was concerned about the power usage. I have a 750 Watt PSU
MONITOR RESOLUTION: 1920x1080 Resolution
ADDITIONAL COMMENTS: Would like to run most games at 1920x1080 the Primary games I will be playing are listed above.
It's a PCIE 2.0 system which means the x4 isn't a big deal. It really shouldn't limit an HD6850 at all. There's a fair number of articles on the subject if you look around.
Also your PSU can easily handle 2 of those cards.
That said waiting a few weeks and getting an HD6950 or HD6970 is probably a better idea. It is always best to use crossfire/sli as an upgrade path rather than a starting point.