I have a PCI-E 2.0 mobo and a Saphire HD 6960 2GB video card that is running 3x27" screens. It can pull most games on medium in an Eyefinity, however, I would love to upgrade so that I can run it at High or Ultra settings.
I have been considering getting a new video card, however, I don't know whether I should go all out and buy a whole new PCI-E 3.0 setup, seeing that it is x2 the speed of a PCI-E 2.0 or just buy a NVIDIA GeForce GTX 780 Ti for my PCI-E 2.0 mobo and deal with whatever performance I get out of it.
This is a great question, and one that I can answer quite easily: no, you don't need to upgrade, your motherboard will be fine.
Sure, there are benefits to upgrading to a fresh new motherboard, but the bandwidth required, and what you will get out of it isn't worth it. There are some very, very slight performance improvements that the third generation of PCIe offers, but it's not worth the $200+ on a new motherboard.
My recommendation: Buy that awesome NVIDIA GeForce GTX 780 Ti, and leave your motherboard upgrade for after Computex, which kicks off in June.