Gaming Rig for $2000

the hx750 will run ure system or add little bit overhead for 850hx

Twin 6950s might provide slightly better performance at high res, while using less power/generating less heat at roughly the same or a little less cost.

I just looked up the 6950 and i saw that they could be unlocked to be 6970 is that true?
Also, i'm thinking that this motherboard might be over kill. Is a NF200 controller really necessary?

Yes 6950s can be unlocked. But not all of them. Only the reference design 2GB models can be unlocked (which also come with a dual BIOS switch). The other 6950 2GB models can be overclocked to perform at near 6970 stock levels.
Imo 6950 2GBs @ 240$ each would be better value over the 560Ti also performing much better than them at high resolutions.

U r looking at very little performance difference at 8x and 8x over 16x and 8x so its really upto to get a mobo with NF200.

Eburta:

1. With reference to the above ..... Yes, if you go to 2560 x 1600, the 69** series should be looked at, but the 560 Ti has the best ROI (return on investment) at the your resolution.

Using Guru 3D's game test suite (COD-MW, Bad Company 2, Dirt 2, Far Cry 2, Metro 2033, Dawn of Discovery, Crysis Warhead)

Twin 6950's get 759 @ 1920 x 1200 get 759 fps for $490 ($0.70 per frame)
Twin 6970's get 8259 @ 1920 x 1200 get 825 fps for $630 ($0.76 per frame)
Twin 560 Ti's (900 Mhz version) get 862 fps @ 1920 x 1200 get 862 fps for $440 ($0.51 per frame)
Twin 570's get 873 @ 1920 x 1200 get 873 fps for $670 ($0.77 per frame)

2, Make sure you are getting the 900MHz version of the $560 .... not only are they equipped with better coolers so you can easily OC them to 1000 MHz but they are usually cheaper than the reference card. I OC's the Asus one w/o even having to touch the voltage. I also listed EVGA as they are currently the cheapest after MIR, but my one concern is that I have had issues with EVGA as, in my experience, they won't warrant the factory overclock.....been there and had that argument, didn't get anywhere.

Asus 900 Mhz $235 http://www.newegg.com/Product/Product.aspx?Item=N82E168...
EVGA 900 MHz $225 http://www.newegg.com/Product/Product.aspx?Item=N82E168...

stay with the 560 ti's. with those cards you dont need that motherboard go with the asrock p67 extreme4 mobo. 750w is more than enough to go sli with the 560ti