I will be using three monitors:-
Secondly do I really need two Video Cards in order to do this?
No.. There are video cards out there which will allow LUT support for 3 monitors, namely the ATI Eyefinity series. But there's more to it than that. Depending on how much power you want your GPU to add to the equation, what kind of color management software/hardware you want to use, what connections your monitors are equipped with, and so forth. Keep in mind with ATI Eyefinity series one of your monitors MUST be a Displayport monitor.. or you must use an active DP to DVI or HDMI adapter.. both of which are now fairly inexpensive and available where they weren't before.
Your monitor selections confuses me. The Eizo I got, you have it already. The NEC model you quote has been replaced by the PA241w. The Dell.. it's not in the same realm.
The NEC is best calibrated with the Spectraview II software and puck using it's internal LUT. All you'll need is a DVI output, not necessarily one with a video card LUT.
Video cards use a lot of power, make a lot of noise, a serve as unintentional air-blocks in your case.. impeding thermal air flow. It would be better to get away with a single card setup if possible.
When you say "high-end graphics" what do you mean? How much video editing compared to image editing?
Unless you're doing mostly video editing there is very little advantage to your expensive 990 CPU and it's six cores over the newer 2700k Sandy Bridge with its four cores. And it uses a good bit of power, generates more heat, and no matter how you look at it.. is several generations old. Even if you were doing a lot of video editing, if you're not over clocking, the 970 is the better value by far.
It would help if you prioritized your use. What percentage of video editing and size of your files, what percentage of image editing and file size, and what percentage of "high-end graphics" you'll be doing.
Have you considered building your own?