just saying

I have 2 580's and pending reviews , I plan to be getting a 3770k \z77 Sniper 3 with a plx 8747 chip ,[could go for tri maybe]. x16 + x16 or x8x8x8., and will have true pci-e 3.0 down the road ,when the cards get updated.
-had planned on a x79\3820 but they seemed stressed at 4.8 let alone 5.0 my target 7\24 oc on a new system.
notes: I have highish end water so cards never hit 40c @ 900 , moving to new cards[x2] mean new block's for me [gtx680 are not worth it IMO] , I like the low temps. and a cool room.
-at 2560x1440 580sli are not choked by any game , I only use the 900 profile for bf3. but the system minus cards needs a update.
-on paper the plx chip looks better than the nf200 even when run @ pci-e 2.0

-in your case you could even just go the z77 sniper3 and keep the 2600k [unless you were selling it.] - high end z77mb only $350.00 upgrade? ,then look around when you need new cards and feel a need for a new platform.
-good luck