Upgrade Advice - Video & stop or CPU & MB

Hello

I want to upgrade my video card GTX 285 OC with the new GTX 680.
My question is do I just upgrade and stay at PCI Express 2.0 or upgrade to a new CPU & MB that supports PCI Express 3.0
or wait till later. If now what CPU & MB?

My current system is

CPU i7 OC to 3.8GHz
RAM 12GB OC 1333 to 1533
Video BFG GTX 285 OC
SSD Crucial drive 240 GB
Dell 30" Monitor

Thanks for any info.