7950 cf vs 7970 cf vs 7990 vs 7970 6gb cf

i am going to be upgrading my gpu's but im wondering as i will be running 4 monitors and using 3 of them for gaming 1920x1080 x3

was wondering which would be the best for me out of the title?

aswell as i would be in the future upgrading to 6 monitors and probably stick to 3 monitor gaming as 6 monitor gaming may be not my type due to the layout

never theless i was wondering the performance difference between

7950 CF

7970 CF

7990

7970 6gb version CF

i will be making most of these purchases early summer so i am also taking into consideration the 8XXX series as i know eta for them is late 2013 or 2014 but than i also thinking of possibly waiting for the next series and buying high end gpu's from the next generation

my gpu budget is limited to 700 pound

preferably around 600pound range( i know 7990 is at 700 range)

and hopefully that the gpu's would last a few years

i dont mind if i am unable to max out every game while triple monitor gaming

other uses things that i would use my computer for does not matter for me if its tad bit faster which consist of unity/udk/crytek engine visual studio and possibly playing around with game server hosting 

aswell as rest of my build is

amd 8350

asus sabertooth 990FX mobo

16gb ram @ 1866

ssd 120gb kingston hyper x 3k

800W psu single rail 80+

aswell as i am pondering on the fact would pcie 2.0 bottleneck or be near to bottle necking the gpu's

i know amd has given a statement that a single 7970 does not get bottlenecked comparing to pcie 3.0

but i am thinking does total gpu power count on a single pcie slot or aslong as the card inserted into the pcie slot dosent get bottlenecked as a single wont be bottlenecked when using CF

along with that wondering if 7990 would be bottlenecked by pcie 2.0

 

SIX MONITORS?!? You sir, have too much money. I would advise you to buy the 7990 if you can afford it and your PSU can handle it, it's basically two 7970s stuffed into one case. If you want to save some money, one 7970 will run most games in eyefinity at medium settings.

mainly will be going to six monitors so it is easier to play around with engines+information files open as i am currently just studying games development aswell as looking at stock market is much easier with as many screens as possible just macro up to open everything and its great