PC Runs Slower

[Hyperr3121]

Hey, I need some help as I've been having a little bit of an issue, and with my limited knowledge of how to fix this, I'd like to ask you guys.
Here's my situation:

I built my gaming pc in August 2015, Specs are:

CPU i5 4690k

GPU GTX 970

Motherboard MSI z97 Gaming 5

RAM 2x4gb HyperX Fury

PSU Corsair 700W

HDD 1TB WD Black

Corsair H60 Cooling for my CPU

NZXT H440 for my case

From about beginning of December 2015, I've noticed that I have been dropping frames in games. I mostly play CS:GO, and i used to run it fine on 300fps-ish, however now I run it at 100-200, whilst nothing else but CSGO and Steam open.

I also used the MSI Gaming App to boost my CPU speed from the standard 3.6gHz to 3.9gHz. I've read that 4gHz is the limit, so I didn't want to go past.

Could the problem be that I've damaged my CPU by overclocking it?

Usually when my computer is on, and I'm not doing anything, I get around 30-35 degrees Celsius, and when I game I get around 35-40.

Any help would be greatly appreciated and I'm greatly looking forward to any replies,

Pawel.

 

[YoungColieo]

The frames dropping is most likely not because of your cpu but because of your gpu. Dont think because you overclocked your cpu it would be "bad" now, but it is possible.

I would run diagnostics on your gpu and update drivers. If you have any more questions I would be happy to help.

 

[Hyperr3121]

The frames dropping is most likely not because of your cpu but because of your gpu. Dont think because you overclocked your cpu it would be "bad" now, but it is possible.

I would run diagnostics on your gpu and update drivers. If you have any more questions I would be happy to help.

What would be the best way to run a diagnostic on my gpu?