Aw, thats not the answer I wanted to hear
Thanks for the info though, interesting you are running an i5 and not having problems. I'll have to check out my motherboard and PSU ina bit more depth and make sure I could support something like a 780ti.
Personally I'd wait a bit before spending quite a bit of money on a 780ti. Afaik we don't really know which cards will support the announced VR enhancements like SLI. If that turns out to be only supported in the new 900 series then that would make those a better buy for someone with a rift. If they've said the enhancements will include the 780ti then ignore me.
I've always been a bit dubious about SLI and Crossfire. But if those manufacturers are talking directly to Oculus and if you are really into a game like Elite, where the manufacturer is clearly joining in as well, then it might be worth considering in this sort of decision.