Dunno what's the beef with 3820, even with the limitation compared to "k" cpus, I was able to easily oc it to 4.3ghz without messing too much with voltage and memory clock and that's decent enough oc.
I am using Gigabyte x79-UD3 with 680 SLI, I've done some research before deciding on the x79. This is the only mobo that give me 2 PCIE 3.0 slot, separated by enough space for SLI that I can easily fit 2 x 3slot 680 cards to run cooler with less noise, and with enough space in between to put in another pcie x 8 card if I need to. And this is a pretty basic mobo that's not priced like extreme gamer mobo.
For Z77, you need to have ivy bridge to run pcie 3.0, and most of the pcie spacing is not ideal. A lot of the pcie 1 and 2 are too close to run 3 slot card, and if you use pcie 1 and 3 for example, one of the slot may run at only 8x speed. Anyways, that's the situation when I was looking for a board, maybe there are now ones with better flexibility.
But just based my experience, you can build a good sli system with x79 boards, with a no frill mobo like x79-ud3. Yes there are bunch of "gamer" mobo from z77 that give you a bit better flexibility with pcie slots for sli, but you'd have to pay premium for it.
Bottomline, the cpu, chipset all perform similar. It's the feature on the mobo - for me, it's the pcie slot arrangement that will determine the best fit. I learned it the hard way already with my 7970 crossfire that 2 high powered card next to each other is not a good thing, especially running them at full load. The board that put those cards as far away from each other gets my money.