You have selected a CF / SLI capable MoBo and a PSU that can't support a 2nd card.....Move up tot he XFX Core Edition 750 or 850
$90 750 watts
http://www.newegg.com/Product/Product.aspx?Item=N82E16817207015
$100 850 watts
http://www.newegg.com/Product/Product.aspx?Item=N82E16817207011
Last week they were $20 cheaper
..... but their quality has made them very attractive and my guess is that demand is starting to outstrip supply. ..... both get 9.5 performance rat8ngs from jo9nnyguru.com
If the goal is gaming, the price premium you're paying for the 2600k is wasted .... the 2500k makes more sense if budget is an issue.
Case - I'd suggest the Corsair 500R based upon recent reviews at Tweaktown and benchmarkreviews
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&N=100006519&isNodeId=1&Description=500r&x=0&y=0
Alternately, the HAF-X / XFX Combo costs $280.,....This antec pairing is $15 cheaper and is extremely quiet and cool running.....having built with both on several occasions, I prefer the DF over the HAF-x
$145
http://www.newegg.com/Product/Product.aspx?Item=N82E16811129087
$120
http://www.newegg.com/Product/Product.aspx?Item=N82E16817371024
The CP-850 is specifically designed for and fits in just 4 antec cases and the pairing results in an unusually quiet and cool system.
http://www.silentpcreview.com/article971-page7.html
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story4&reid=142
It is completely unmatched by any ATX unit on the market I can think of. You'd have to spend twice as much as this thing costs to find the next best thing, performance wise.
RAM - Low profile, no tall heat sinks to interfere w/ CPU cooler
http://www.newegg.com/Product/Productcompare.aspx?Submit=ENE&N=100006519%2050001459%2040000147&IsNodeId=1&bop=And&ActiveSearchResult=True&CompareItemList=147|20-233-186^20-233-186-TS%2C20-233-196^20-233-196-TS%2C20-233-199^20-233-199-TS
CPU cooler - Hyper 612 PWM or Scythe Mugen 3
http://www.newegg.com/Product/Product.aspx?Item=N82E16835185168
http://www.newegg.com/Product/Product.aspx?Item=N82E16835103103
GFX - You pick
Guru3D uses the following games in their test suite, COD-MW, Bad Company 2, Dirt 2, Far Cry 2, Metro 2033, Dawn of Discovery, Crysis Warhead. Total fps (summing fps in each game @ 1920 x 1200) for the various options in parenthesis (single card / SL or CF) are tabulated below along with their cost in dollars per frame single card - CF or SLI:
$ 170.00 6870 (434/701) $ 0.39 - $ 0.49
$ 240.00 6950 Frozr OC (484/759) $ 0.50 - $ 0.63
$ 320.00 6970 (526/825) $ 0.61 - $ 0.78
$ 215.00 560 Ti - 900 Mhz (495/862) $ 0.43 - $ 0.50
(2) 6870's get ya 701 fps at 49 cents per frame
(1) factory OC'd 6950 get ya 484 fps at 50 cents per frame
(2) factory OC'd 6950's get ya 759 fps at 63 cents per frame
(1) 6970 get ya 526 fps at 61 cents per frame
(2) 6970's get ya 825 fps at 78 cents per frame
(1) factory OC'd 560 get ya 495 fps at 43 cents per frame
(2) factory OC'd 560's get ya 862 fps at 50 cents per frame
The 6870's are the clear winner at just 49 cents per frame and 701 fps.....next up (that is, beating 701 fps) would be the twin 560's at 50 cents per frame and 862 fps.