PCIe 2.0 Bottleneck?

Hey there :D

I have a PC that is about 4-5 years old.and it is running a first generation Intel I7 with an x58 chipset. so far, I've kept my motherboard in good condition along with the CPU. Both seem to run smoothly without any problems. The thing is, I've sold my setup of 2 560TIs in SLI to upgrade to a single GPU solution. Here are the specs:

Motherboard : EVGA X58 141-BL-E757-TR [LGA 1366] :
http://www.newegg.com/Product/Produc...2E16813188049R

CPU: Intel I7 920 @ 2.66GHz
http://ark.intel.com/products/37147

Ram: 32 GB Total (6 Slots running 4GB each)

Is it possible to get a GTX 780 running on this system without any Bottlenecks? (If not, then how about a GTX 760?)

Thanks in advance :)