I personally would get a GTX 970
That aside, it really doesnt matter if you got PCI-E 2.0 oder 3.0 as long as you got 2.0 @ 16x. I'm running both my 660 (SLI) 3.0 @ 8x which is about the same speed as 2.0 @ 16x and they work just fine.
Also you CPU is just fine, stick with it.
Just get the card you want.
AMD GPU's are PCI-E 3.0 just like Nvidia right now, the CPU's from AMD on the FX line only support PCI-E 2.0 (I think It might have changed since bulldozer) and your processor, the I5 only has PCI-E 2.0 support but it doesn't matter AT ALL for GPU's really, you won't over saturate the PCI-E lane you're using regardless. Go with the GTX 970 and be happy till you need to upgrade your cpu!
OK thanks for your advice sir!