Welcome to the forums..

Is this your first time trying to watercool? If yes, I'd recommend one of the high-end closed loop systems, like the Corsair H100i, which have been very well reviewed. They provide a lot of cooling power for the 2011 CPU's, don't cost the earth and don't have the associated risk that comes with building your fist water loop.

However, if you wanted to go down the custom route, something like the EK-KIT H30 240 HFX might be what you are after, as it comes with everything you'll need.

What case are you using? This will affect the size and thickness of radiator/fans you can fit in to cool the system.

As I posted in another thread. It would help us greatly if you told us what case you're using, and what parts you are running, and perhaps a budget, so we can get an overall idea of what would be the best for your set-up.

this is what i am thinking of getting and there is no price range the more it cost the better i want to go extreme and for case i cant decide between Cooler Master Cosmos II or corsair 800d which one is better thx

CPU Intel Core i7 Extreme Edition i7-3970X 3.5GHz
CPU Cooler:Corsair Hydro Series Extreme Performance Liquid CPU Cooler H100i
Motherboard: ASUS Rampage IV Extreme
Memory: Corsair Dominator Platinum 64 GB (8x8 GB)
Storage: Western Digital Caviar Black 2 TB
Storage: Western Digital Caviar Black 2 TB
Storage: Western Digital Caviar Black 2 TB
Storage: Western Digital Caviar Black 2 TB
Storage: Corsair Force GT 240 GB
Storage: Corsair Force GT 240 GB
Video Card: ASUS GeForce GTX690 X2 or 680s
Case: Cooler Master Cosmos II or corsair 800d
Power Supply: EVGA SuperNOVA NEX1500 Classified 1500W Modular
Optical Drive: Pioneer 15x SATA Internal BD/DVD/CD Burner
Monitor:Asus VS247H-P 24-Inch
Operating System: Microsoft Windows 8 Professional Full (64-bit)
Keyboard:Thermaltake Esports Challenger Pro USB Keyboard
mouse :Mad Catz R.A.T. 9 Professional Wireless Gaming Mouse

Extreme WC would be TEC cooling but I guess you're new to WC so you shouldn't wander in to this.

How much are you going to cool? The basic WC blocks that are useful are the CPU, GPU and Motherboard blocks. Some cool the ram as well but this is not needed.

For an extreme cooling system I would say that 2 360 rads with 2 D5 pumps in dual loop setup where one 360 cools the GPUs in one loop and one 360 cools the CPU and the rest.

To fit most parts knowing a bit about modding will be required.

when you start to dismantle the mobo and vid card then you void your waranty.
if you fk enny thing up you will not get a new one back from RMA or enny thing like that.
is it damaged you have to buy a new one.
and those Corsair Dominator Platinum i dont think you can put them on water, if you can i recomend to mail and ask corsair to be shure.
for heavy OC you need 240 rad on each OC'd part so you need a case that have space for a good deal of rad's
fans whit good static preshure, case whit good airflow, a fan controller, monitoring your flow and temp on the water.
this build WILL cost you a good deal of monney.
how mutch are you willingly to use on a case if the ones your tought of are too small or not good enough for WC and airflow? ( if thats an option )

maybe you can use the new corsair 900D instead of the 800D

so far cases are cosmo 2 or corsair 900d

I have a Cosmos 2, and though i love the case overall, there are some significant issues with water cooling (the space on the top will only fit a very thin rad for example, and modding is required to allow for a 4x120mm sized rad on the top).

Also the hotswap bay is probably going to be 'in the way' when water cooling...
and the 3 5 " bays at the top might have clearance problems if you try to use a 2 by 5" bay res...

To make it workable, you're going to need to put your rads in the bottom of the case (i was eyeing those ultra thick 80mm 2x120 rads myself... 2 of those in series should really be something...)

I'm a bit concerned about airflow in that bottom compartment.. (the vents in the side doors which would be inputs/exhaust for your radiators are there but not really large enough imho.. more modding possibly on the doors to open these up..

I really do like this case, but for an 'extreme' water cooling setup, it may not be appropriate. I urge you to read some reviews on it.