All you mention is CS-GO for gaming for the most part.
For your current setup, Id only recommend looking for a good deal on a kit of 2400 or 2666mhz ddr3 ram. Should help with the smoke FPS drops, but overall, potentially a minor noticable upgrade.
Your motherboard only supports 2xxx and 3xxx intel chips, so a 3770k is the only real chip upgrade, of which is wiped out when you overclock.
Id try to find a cheap 6xxx or 7xxx based intel combo deal. They exist on here occasionally, even saw a freebie setup recently that might have ended up being simply bad ram.
Keep your eyes open!
Your GPU is perfectly fine for playability, even if you chose to find a high refresh 4k monitor in the future.
Right now, you are going to want to look for a processor that has more L2 and L3 cache. If its an intel chip, its super easy, just google the name, and 99.9999999% of the time, the very first result is the Intel data website on the chips.