Sudden CPU/lag spikes while gaming

[strime]

Hey there!
I'm having a really annoying problem that I hope someone's able to solve for me.
My problem is... When I'm playing games, my FPS tends to drop a WHOLE bunch.
I don't know what's causing this problem... I go from a steady 100-120 fps to 30 fps mid-game. Then some seconds later, it goes back to normal, then again repeats itself after a minute or two (Sometimes even seconds after).

The specs I have:

i7-4970k @4.0Ghz
NVIDIA GeForce GTX 970 4GB DDR5
BIOSTAR H81MGV3 (Motherboard. Needs to be changed, I know)
16GB DDR3 RAM @1600Mhz

Also... I took some screenshots from my last gaming session. I'm kinda worried about the temps, so I don't know if that's causing it?:

CPU - Usage/Temp: https://gyazo.com/f8a7d92463aa34daf2dee42af14c85ff

GPU - Usage/Power/Temp: https://gyazo.com/2c72e596002d7f7dae4c06d1f3a49962

Any help is appreciated! Thank you very much!

 

[Shektron]

Run AIDA64 FPU stress test and see if your CPU is thermal throttling or not. It does seem that your processor is overheating. What cooler are you using?

 

[strime]

Run AIDA64 FPU stress test and see if your CPU is thermal throttling or not. It does seem that your processor is overheating. What cooler are you using?

I'm not actually sure, as I bought the PC sampled without the cooler being specified.
I hasn't always been like this though. Hence my confusion. It does seem like a stock cooler tho.

 

[Shektron]

Well a stock cooler can easily be differentiated from aftermarket cooling. It'll have an ugly blue sticker with Intel written somewhere. Send a picture if you can't figure it out.

 

[strime]

Well a stock cooler can easily be differentiated from aftermarket cooling. It'll have an ugly blue sticker with Intel written somewhere. Send a picture if you can't figure it out.

I did the stress test and it did indeed throttle/overheat. I stopped it when it went over 100C.
Also, the CPU cooler is from a company called XILENCE in Germany. Can't seem to find the exact model anywhere, but I've taken a picture of it.

Pic: https://gyazo.com/65a56e5587d34b640d6007f4c02b6d5d
(A lot of dust. Been a month or two since I've cleaned it)

 

[Shektron]

Well since it's overheating so terribly I suggest you get a good cooler for the chip, fix at least the overheating.