As far as I am concerned, the most important thing about a good gaming rig that is also cost effective is just this: BALANCE.
Right now you have a pretty balanced system with, in fact, only a slightly underpowered GPU. CPU is fine and is not your bottleneck. Sure, the 7850 cannot push every detail level in every game. But consider whether it is worth spending a major amount of cash just to have every slider on Ultra in every game; you are paying a premium for a real world difference that is negligible. Tweak your settings per game and you will (and I am absolutely convinced of this) have a 60 FPS locked situation at more than reasonable detail settings on an i5 + 7850. And if you were to do a side-by-side comparison of your old and new tweaked settings, I reckon you'd hardly see the difference.
The above settings tweak is also what you need to do to make a sensible choice; knowing what difference you are actually talking about. Because up till now all I have seen in this thread is a shitload of assumptions about personal life/situation that really add nothing at all to any sort of discussion, and people recommending CPU upgrades 'because you game at 900p'. Seriously?
In my view if people ask for advice you want to give them a cost effective advice, any other advice just bores down to 'buy the most expensive parts and stick them together' which is pretty damn worthless advice in my book. Others have also said this: get the right tool for the right job. Get a balanced system, keep it simple, and let go of the idea that have every slider at ultra is the best experience, there are quite a few games where it is definitely not, or where the components required to achieve highest settings at playable FPS will cost you six times the money of playing at 'High'.
It really doesn't matter what name you give it, but buying into the ultra high-end is never a sensible choice for gaming, which is how the term 'overkill' actually got popular. Internet heroes that think they need to compensate for something spend 3K on their rig to show off benches and see negligible advantages over someone with a rig that costs 1/3rd of the price. You decide for yourself whether you prefer common sense over spending 3K to be the top dog for a few months.