GTX 680 SLI or GTX 690 - will an i7 970 bottleneck it?

I just got a pretty good deal on an i7 970 on ebay, it was bundled with an older x58 mother board so I can use my old i7 920 and GTX 470's as a 2nd PC to do some HTPC, Dedicated Flight Sim, Cluster Computing, or LAN stuff with friends with and not have to worry about performance but that is besides to point.

I plan on going back to watercooling my CPU so I hope to get the 970 to at the very least 4.0ghz although I really don't want to go crazy with it so keep in mind I should have a mild overclock on this system I plan on upgrading. Right now my main concern is what I should do graphics wise, Ideally I am trying to avoid any bottleneck and have the ability to upgrade to multiple monitors or a higher resolution monitor at some point (I currently have a 23'' 1920x1080 120hz 3d monitor).

Like I said I want to do some distributed CUDA computing so the GTX 690 does sound quite tempting since I can ultimately fit more cards on my mobo but the idea of spending that much money right off the bat has me a little hesitant.

Anyways here is what my system will look like after I get back from deployment and upgrade to the i7 970:

Core i7 970 @ stock-4.0ghz under water
Rampage 3 Extreme
12GB Gskill 2000mhz DDR3
intel 40gb SSD Boot drive
More 1-2tbs HDDs than you want to known
2 GTX 680 or a GTX 690
Coolermaster Gold+ 1200w PSU
23'' 1920x1080 3D Vision Monitor (Asus)

Also do you think once I get to around the point of 1 or 2 GTX 690s or multiple GTX 680s I should really look into upgrade to PCIE 3.0?

thanks for the fast responses + rep!, I firgure 350 shipped for a used i7 970 and an Asus x58 mother board was a good enough deal that I might as well not pass up on it even though I was really looking forward to updating to a new PCI-E 3.0 platform at some point. that being said I can still salvage my old i7 920 system for some folding or distributed computing or just sell it and recoup some of the costs associated with the 6** series. at this point I'm looking more for a gtx 690 because if I ever decide to SLI those before I get a new motherboard/cpu I can use the full 16x16 PCI-E bandwidth and not worry about getting knocked down to 16x8.

thanks for the input on the boot drive. you are absolutely correct. with the prices SSDs are at lately I think i'm going to make the jump to maybe a 128 if I can get it for around 100 once I redeploy so I can get rid of this 40gb and keep it as my boot drive on my i7 920 system. that 40gb was getting rather cramped...

thanks the wonders of ebay! Its nice to have packages waiting on you getting home from deployment, I wont be able to get to my storage unit soon enough to get on some battlefield 3.

now the challenge is going to be finding one of these "ROG expanders" that add 4x SLI capabilities to the Rampage 3 Extreme, wish me luck lol

I'll look into that with some benchmarks, I was originally going to go with a few 7970s because from what I understand they do really well on pyrit so I assume they would do well folding aswell but that would pretty much negate the whole 3d vision system I have so I decided to stick with green since it really hasn't failed me to date. worst case scenario a 690 holds it value pretty well so I can always trade or sell it for something else.