yep. ac4 and cod are both cpu bottlenecked games... poorly optimized rellying on fast cores... furthermore your resolution is so low ANY gpu will be bottlenecked by the cpu at that resolution, no matter what cpu you use for the most part. Frankly, that gpu is too much gpu for your resolution. a hd 7770 is too much gpu for that resolution.
Save some cash, buy a $70-$80 hd 7770, it will allow you to play every game ever made at full graphics candy and 1366x768... and take the rest of your saved cash, buy a 1080p monitor, it will let you play most games on high at 1080p, and those it struggles with you'll be mostly cpu bottlenecked anyway.