Best graphics card configuration for $750.00

Thats pretty much it. I have $750.00 to spend on a new graphics card and want the best. I really don't care if it is one or two cards nor do I care AMD vs Nvidia. My current pc specs are on my profile, what do you all think? 

Your monitor is 144hz? You should probably get a 780.

You could go dual 7950s, or something similar. However, the 780 is a beast card, and it will leave upgrade paths for 2way SLI.

SLI 770 will give you the best preformance But you would need a bigger PSU for that and if you wanted one of THESE you would need to make sure it also has 42 amp 12v power

Without a PSU Upgrade I'd say a 780 is your best bet seeing as you really cant have dual cards with your current power supply.