Good choice swapping to 680's. Are you using the same drivers as you were on the 690? Have you run any quantifiable tests to compare the setups like 3dmark or heaven? Just watching fps bounce around in games isn't a great measure. 

schulmaster

"Good Choice" is situation dependent at best. Some people use their motherboard expansion for, dare I say it, non graphics hardware. The OP has sacrificed his ability to do so, and has incurred a performance decrease for his trouble, not to mention the tainting of heat and power figures. In this case, there is certainly less good than choice. Double Reference VRAM is awesome to have, but with it your ability to memory overclock is significantly hindered, and additionally latency is increased. Only using 600MB past the 2GB threshold at the OPs res means pulling back even a single post process, like AA, DOF, HDR etc, the VRAM would be unnecessary, making the single card solution very appealing.

 
I've owned both 690's and 680 classified's, and I can easily say I'd take two classies over a 690 any day. From my experience, the 690 runs exponentially hotter, louder, with hindered overclocking ability and the obvious only 2gb of vram. If you have the cash and space, dual classified's are easily the better option. You'll also be able to overclock the ram on a classified as well, if not better (due to lower temps) than the ram on a 690. 
 
Now I'm just wondering if he's ran some benches comparing the setups. 

Something is definitely wrong if your framerates are half. One of the GPU's must not be working, or you don't have SLI enabled, or something like that.

When you say everything maxed what exactly.
 
If you have everything set to Ultra, 4X MSAA, Anti-Aliasing (POST) High, Motion Blur On, Anisotropic 16X, and HBAO you wont get that great of frames in BF3. With all of that it is very demanding when your running at 5760x1080. I'm running 3 GTX680's and cant run those setting and stay above 60 fps (Vsync On) all the time.
 
The new DLC Aftermath is pretty tough on the video cards at 5760x1080. 
 

JerkMan

I'm actually considering a third 680, so you're a good source for info. Do you have the 2gb or 4gb versions?

 
I'd recommend figuring out why your second 680 isn't working at all before you buy a third. Lol

I've run checks in Precision X, GPU-Z and HWMonitor. They all say both my 680s are peachy, with the listed OC. I'm thinking user error at this point. When I switched from my 580s SLI to the 690, it must've auto-reduced the settings (from all maxed at 1920x1080 with Fermi), I'm thinking to medium all around, and I honestly got too excited to check it. Then when I swapped to the 680s, the game adjusted accordingly, upping the settings thereby reducing the framerate.

I noticed the above in BF3 because going from ~120 FPS to ~95 FPS caught my eye. Even then I didn't check the settings, jumping the gun and assuming it was a PCIE issue and getting the Sniper 3. As far as AC3, I think like you said above, it's not accurate at all to watch frames jump around, for sure in the ~25 to ~40 mark where any percentage jump wouldn't be noticeable under say 20%-25%, meaning 10 FPS. I allowed my mind to play a trick on me.

The blessing in disguise is that I've got PCIE 3.0 x16x16 with Sandy Bridge, and may not even upgrade to Haswell (and a new socket/MoBo) unless I see a drastic result over my setup (I'll wait for the pros to sort that one out). All that's certain in the near future is a 2600k overclock, which should be a breeze with this board once I have the time.
 
Having said all that, from the sound of it BF3 (the one game I play constantly) doesn't scale that much better in tri-SLI over SLI. I'm getting the same roughly 60 FPS with my two. Not thinking it's worth getting a third just yet.
 
Another thought... Could my VRAM make up for the lack of a third card, pushing my performance up to tri-SLI? Again, I was in the 2600s MB VRAM usage yesterday according to Precision X...