Advice on a new rig

[Sp_i_ke]

Hey guys,

I've been multiboxing WoW (5 toons) for about two years now. I just startet setting up my first ISBoxer pro setup, still a work in progress but getting there.
With the recent WoW sales in December I got my self 5 extra accounts to 10-box, but my rig just isn't up for it. I've set all 10 instances to the lowest graphical settings, and as long as I walk around outside of the cities I get frame rates on my main of about 15 to a max of 20. But if I dare to enter the city my fps go down the drain to completely unplayable. I decided to OC my processor (i7 2600k) to 4500 MHz which makes to whole thing halfway playable but far from satisfactory. Also with Warlords of Dreanor, and it's UI and Char updates on the way I'm really in need of something new.

First a look at my current setup:

Asus P8Z68 Deluxe
Intel Core i7 2600K @ 3.40 GHz - be quiet! Dark Rock Pro 2
Corsair Vengeance PC3 16 GB DDR3 1600MHz
Asus AMD 6970 CCU
Corsair PSU AX850
All tugged nicely in my Silverstone Raven RV03 Case

This rig will go to my wife, she recently started five-boxing.

My Logitech G13 and G19 as well as my Madcatz MMO 7 will be joining up with the new toy.

The new rig should be capable of playing 10-15 sessions of WoW (planning on doing some 15 boxing with my wife 5 accounts as well). As soon as I get a better Internet connection streaming should be possible as well.
Atm I have 4 monitors attached to my rig (see picture below). A 30 inch center flanked by 2 20 inch in Portrait and a 3rd 20 inch on top of my center screen (all Dells). May want to ad two more monitors in the near future. So will need enough monitor outputs.
I see some multiboxers still playing with/having 2 or more computers to box with, is there still a use for this?

Reading the forum and watching some of MiRai's very informative videos I've already learned that nVidia is the way to go, since SLI also supports Windowed mode. One or better two 780 ti sound like a good basis to start with (red there will be a 6 Gb version available shortly, would it be useful to get those instead of the standard 3 Gb?).
That about where to knowledge ends. I red a lot about the X79 and Z87 chipsets but have not been able to find any conclusive info on which is the best to go with.
Here and there I red some little pieces about RAM-disks, sounds interesting.

Fund wise lets start with a budget of 2.000 to 2.500 Euro. Budget can be flexed if needed.

I'm planning to purchase in about 1-2 months. Having hopefully the last big exam of my life on the first of march, when I pass this will be my reward

Thanx in advance for all your advice,

sP`!´Ke