First time building Computer, High end gaming Pc

[Risen91]

Hey, this is my first time custom building a Pc and I want to get it right without any screw ups haha. Can anyone tell me if these produces are compatible and any good, my Budget is about £1500 ($2386.5) I have a vague idea of what I'm after but just want to check things over before I commit to building this . Any suggestions or advice is greatly appreciated!

-COOLER MASTER COOL HAF 932 (not sure yet, but want a high end cooling case to keep that beast of a graphics card from heating up the rest of the case)
-Asus MAXIMUS IV GENE-Z/GEN3 Motherboard (Not decided yet, but had a look at this one. If anywhere this is where i need some advice)
-Intel i7 2700k (wanting to overclock this to about 4-4.5ghz)
-G.Skill Ripjaws Z 16GB (4x4GB) Quad Channel Kit DDR3 2133 PC3-17000 RAM
-Sapphire Radeon HD 6990 graphics card (possibly in overclocked setting)
-OCZ 120GB Agility 3 SSD x2 (Possibly in Raid0)
-Corsiar HX1000W PSU (not sure on system wattage yet but pretty sure i need 1000w)
-Corsair H100 Hydro CPU Water cooler (Maybe the H80/H70 but i would like to try for a higher CPU overclock if possible)

Thanks in Advanced!

[Risen91]

quick update, motherboard is now properly going to be the Asus Maximus IV Extreme. Still need any advice thanks

[Transfusion]

Close to top-of the line parts-you can't really go wrong here.
Here is a neat PSU wattage calc for you to use: http://extreme.outervision.com/psucalculatorlite.jsp

The only thing I can think of is that the HD 6990 costs $699, whereas 2 HD 6950s in CF cost $500. The HD 6990 only has one fan cooling 2 GPUs attached to 1 heatsink, so noise may be an issue; if you are planning to overclock then heat will definitely be a problem.

2 HD 6950s may in fact be quieter and your overclocking potential will definitely increase. At stock clocks the HD 6990 will pull ahead of this setup in some applications due to it having higher clocks, but when overclocked the HD 6950s are in the lead.
I don't think its worth +$200 to save a single PCIe slot.
2 HD 6970s cost ~$710 and definitely outrun the HD 6990.
Also:
Asus Maximus IV Extreme
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131700 ($289.99)
2700K
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115095 ($339.99)
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i7-3820
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115229 ($309.99)
Asus Sabertooth X79 LGA 2011
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131801 ($329.99)
About the same price and you can upgrade to Ivy Bridge-E when it's released, if you are a high-end enthusiast...

[Risen91]

Thanks for some great advice, did you mean if both the Radeon 6990 and 6950 SLI are overclocked then the 6950s will be slighly ahead? Or did you mean if the 6690 is stock and the 6950s are overclocked?
At the moment the 6990 card I'm looking at works out cheaper than the 6950 SLI configuration.

[Transfusion]

The overclocked 6950 Crossfire will be ahead if you compare it to an overclocked 6990 and may have a longer lifetime than the 6990 due to far better cooling.

[Risen91]

The overclocked 6950 Crossfire will be ahead if you compare it to an overclocked 6990 and may have a longer lifetime than the 6990 due to far better cooling.

That's cool but the only thing I'm worried about is trying to unlock the 6950 into the 6970 i have heard mixed outcomes on doing that and don't want to mess things up. Apparently to unlock them I need to "Unlocking the additional shaders is done by flashing the card with a HD 6970 BIOS" there is a great tutorial here http://www.techpowerup.com/articles/overclocking/159 but I still worry about messing things up .
The 6950's I'm looking at currently are XFX Radeon HD 6650's and i think i read somewhere that they cant be unlocked to make them into 6970s so I'm not sure what to do.

Edit: Just found this "I have personally used the following method on an XFX 6950 reference model, and an MSI R6950 Twin Frozr II which doesn't have a bios switch, and does not function with a reference bios." So i guess the XFX version is a no no

[Transfusion]

You don't need to unlock any shaders if you are not comfortable with flashing the card's BIOS; simple overclocking already does wonders:

HD 6990 GPU-Z (Note that the fillrates are for a single GPU; it works out to 56.4 GPixels/s and 140.8 GTexels/s at stock clocks for the 6990)

HD 6950 GPU-Z overclocked (Note that the fillrates are for a single GPU; it works out to 58.8 GPixels/sec and 162 GTexels/sec for 2 HD 6950s)
The HD 6950 can go even further:

http://www.techpowerup.com/reviews/MSI/HD_6950_Twin_Frozr_II/31.html Max temps are 71 C. Impressive.
http://www.techpowerup.com/reviews/ASUS/Radeon_HD_6990/25.html
91 C when overclocked. Not good.