cuz the 590 is cheaper in my country and also check out the geforce site and go on the performance tab and in 3dmark vantage gtx 590 wins by about 1000 points. but if the gtx 680 would cost less i would buy it
What about the cost of the 7970 there, does it also cost more? And forget about 3DMark and count performance in real-world benchmarks.
I mean the 7970 and the 680 are really much better choices than the 590, firstly much lower power consumption, then missing the problem with microstutering with SLI/Crossfire.
If you really must get an 590, then yes the 2400 will bottleneck it a little, but if it was the 2500k and oc'ed to about 4.5ghz then you would have no problems.