I assume the 680 is pretty much the only major component common between the two systems?  So that makes the biggest difference being the CPU and chipset.  Chipset really won't do much difference performance wise other than newer features.  For mostly gaming performance, I wouldn't expect much performance difference just because of the CPU.  Hyperthreading will help some, assuming the game engine benefits from it.  PCI speeds on a single GPU setup will make little to no difference. 
 
You don't mention what games you play.  Depending on what they are, if they are more CPU-bound, I assume you would see some performance increase but nothing exponential.  Maybe 10-15%.  I think you may have had your expectations set too high.  If the games you are playing are most dependent on GPU, and that stayed the same I would see no reason to expect huge gains just by upgrading motherboard and CPU. 
 
I would recommend keeping what you have now and picking up another 680.  They can be had for pretty cheap <$200 and assuming games you play benefit from SLI, that should give a nice bump in performance.  The 4770K shouldn't be a bottleneck for that setup either.  Lastly, might want to try overclocking your CPU a little higher.  4.1 is pretty mild, might be able to get a couple more out of it.  I would think 4.4 or 4.5 shouldn't be hard to get.
 
Good luck!

I'm sorry to hear that man, but unfortunately I'm not surprised. I moved from a 920 to a 4770K and while the system felt more responsive and the boot process was better than halved (gotta love UEFI), the faster proc is not something I can notice outside of benches or select programs. The SSD has a lot to do with that I'm sure, and I noticed you have one too. I can notice the difference in Folding@home and CPU-limited games like Civ V or Supreme Commander as it takes longer to bog down, but when browsing the web or doing work in Office? Not really.
 
Same goes for changing an SSD from SATA 3Gb/s to  SATA 6Gb/s, that I only notice when transferring files between two different SSDs because even at SATA 3Gbps speeds, your SSD is limited by the <150MB/s write speed of most existing HDDs. USB 3 was the biggest difference going from X58 to Z87, even installing the OS from a USB 3 flash drive dropped the install time from ~5 minutes to ~3. But it may be some time before we see another CPU performance jump that delivers ENOUGH of a performance improvement to actually be noticeable during regular daily computer use. Even more so with SSDs around. People just aren't going to notice more cores/threads unless they have specific apps they use that can make use of them. 

ssj92
This is the reason I still haven't upgraded. I feel Skylake will be a good time to upgrade if the current system is running fine. If anyone is using a X58/P55 quad-core @ 4ghz+ I don't think a new processor will help much, unless the processor was already bottlenecking the application/game. 
 
My laptops cpu (3840QM) is faster than my desktops, yet in CPU intensive tasks, the end results are only a few seconds - a minute apart at most. 

Well you should upgrade when you have a specific reason to upgrade. Whatever tasks and gaming you do as well as your budget makes the final determination.