Two GTX 780's is really all that matters, I have pretty high end ram, cpu, ssd, and the like, but really it's all the GPU's
Hmph, certainly an overkill for now, but future-proof/4K ready.
I bet there aren't many with specs like you. I am rocking a 7950 Vapor-X and 8350K, coupled with 16 gigs of RAM and a mixture of SSD for Win and a fast raid-0 HDD for the rest. Still in the upper echelons easily IMO, but certainly not capable of smooth 4K with highest details...
Then again, I am a console guy