*Intense facepalm*
As ivogelezarov has already pointed out, there's a HUGE bottleneck in your system. *sighs*
If you bought this system online for a cheaper price than all the other gaming PCs that seemed to be around, the reason it will have been so cheap is down to the fact that it's got a pretty standard (Non-gaming desktop rig) processor and it's obviously going to cause a bottleneck.
(A bottleneck when you're talking about PCs is where one or more components in your PC just can't deliver the performance needed for what you're doing, in this case your processor isn't fast enough to harness the full potential of your GPU (The 760 twin frozr you so keenly mention in your rig)).
I don't mean to insult you but the CPU you're using just won't 'cut the mustard', as it were.
My advice is to get yourself a decent processor, 'm not going to say, "HEY, GECHA SELF AN INTEL, THEY'RE WWWAYYYYY BETTER THAN AMD!" Because a) It's simply not true, they're both great choices and I'm not looking to start an argument here and b) It's about how well your processor can perform, you can't simply judge a processor by how many GHz it can run at.
IN SHORT AND WITHOUT A LOT OF WORDS BECAUSE I'M OFTEN ONE TO GO OUT ON A TANGENT ABOUT STUFF...
Get yourself a better CPU
OR
Maybe put your settings on medium, I hardly ever play on Max settings, you get better FPS (Usually, it depends) if you're running on lower settings.
Anyway, I apologise if this is not the answer you're looking for, and I wish you luck in the pursuit of an answer.
All the best,
Talkii