Im currently deployed atm and im looking to upgrade my two 570's 1.2gb to 2 GTX 680's FTW+ 4gb when I get home.  
My CPU is clocked at 4.0GHz. The rest of my specs are in my Sig block.
If I had to upgrade, I would have gone with the i7-3770k. But that means new Mo-Bo also and im not sure if I want to fork out the extra cash. BUTTTT if I must.... then I must.
 
Update: I am currently running surround with my current setup but don't get fps I want with such little vram from the 570's. works well with some games but can do better. Just wondering if I need a CPU upgrade for the 680's.
 
Any help would be appreciated. Thx EVGA team.
 

i also have a i7 960 at 4.0ghz with 2 680's playing in surround and no bottleneck so far

If you monitor is running at 1920 x 1080 then you'll have no problems at all running the CPU at 4.0GHZ.  I would not push the overclock higher unless you upgrade the Corsair H50 to an H80 or H100.

You dont need to do anything. Your o.c. will handle the cards just fine. I'm at 4.4 on my 920, my brother is "stuck" at 4.0 on his 920. No issues in his setup. We both run 2 x 670 4gb cards at 5760 x 1200. Seriously, it'll be just fine.

I have a i7 930 @ 4 ghz with a gtx 670 4gb. When I was playing BF3 my frames were dropping to the mid 40's most of the time. Upped it to 4.2 ghz and I saw significant improvement. Now I had to bring it back down to 4 ghz because of heat, also I couldn't get it fully stable even with the voltage set to 1.41v. Don't feel comfortable having the voltage that high on a H50. Keep in mind though that BF3 is really the only game I saw an improvement when increasing 4.2 ghz. BF3 tends to require a fast CPU to the get most out of 670's and up. 

In light of the very conflicting information you're receiving from both sides...
 
...try setting up the processing to stay just within the VRAM's limits, score some runs, and then drop the resolution a bit without changing anything else. If things improve significantly, then your CPU is the slowdown (ie, the percentage gain in performance is greater than the percentage reduction in resolution), but if the change is relatively minor then I would hold onto the system until I got the new GPUs to test further.
 
Pay particular attention to your minimum frame rates - in a multi-GPU setup that's where the action really counts and is in the range with the highest probability of wrecking the gameplay. Differences of a percent or two at the top end have no real bearing on the outcome - you want to find out if the team can maintain viable minimums while working together.
 
There aren't many review sites that OC their rigs very far any longer just to review a game, saving such for performance reviews of the CPU/platform itself. Most of them stopped caring between 3.6 GHz and 4...

bvsbutthd101

PurpleReign

So a cpu needs to be at 4.0 or higher in order for it to not be a bottleneck?

Does this mean my i7 950 @3.7 is bottlenecking my 670?

It depends what game you play. Like I said above I only saw an increase in frames when playing BF3. For me, my cpu is a bottleneck for my gtx 670 because I mostly play BF3.  Remember, a bottleneck is only an issue if you're not getting the frames you need. 

...and shows its fullest with single-GPU ops...