This is my System (already paid for*) Help me upgrade it.

Solution
I wouldn't suggest a GPU upgrade unless you really need the extra vRAM or if you enough money to, and having a CPU fan to overclock is not a huge investment. You probably can nice OC off of it. I'd suggest maybe a just an aircooler like the Noctua NH-D14, if you want something on the higher end. Otherwise maybe the CM 212 evo if you don't want to pay that much.

If you do want to upgrade your GPU maybe the 760 or 770 or if those aren't in your budget. Maybe the 270x. Just suggestions for the GPU. Your card is pretty outdated though. I just think having the aftermarket cooler would be a cheaper upgrade in comparison. I think your gpu should handle graphics of stuff right now decently. Not expecting too much though.
I wouldn't suggest a GPU upgrade unless you really need the extra vRAM or if you enough money to, and having a CPU fan to overclock is not a huge investment. You probably can nice OC off of it. I'd suggest maybe a just an aircooler like the Noctua NH-D14, if you want something on the higher end. Otherwise maybe the CM 212 evo if you don't want to pay that much.

If you do want to upgrade your GPU maybe the 760 or 770 or if those aren't in your budget. Maybe the 270x. Just suggestions for the GPU. Your card is pretty outdated though. I just think having the aftermarket cooler would be a cheaper upgrade in comparison. I think your gpu should handle graphics of stuff right now decently. Not expecting too much though.
 
Solution
What? I'm not sure how overclocking would make your guns shoot faster even with a bug... I mean, you'd have to change it through the bios or whatever software you're using at the time. Overall, i think its a pain to change it every time you want to play 1 game.
 
A) you could get easily 4.4 ghz with something like a hyper 212 plus or evo. B) you can set profiles in many motherboards (so you can choose regular or your overclock profile) or you can simply change in the BIOS back to default before you play that game, then change the settings back to overclock when you arent...tedious though.
 
You don't NEED watercooling for overclocking, you just want a better cooling solution compared to the stock cooler. But, you probably would get better results with water cooling, but it also depends on your motherboard. the 212 is the most inexpensive and effective cooler.