New build working great until it suddenly doesn't

Jan 15, 2019
I recently built a new gaming PC and everything runs great 99% of the time. However when im playing most games and there is suddenly a ton of things happening on screen my system seems to really struggle .

For example, I'm playing Overwatch on medium/low settings at 1440p/144hz with FPS capped at 200. The entire game im getting 199/200 FPS, but sometimes when a lot of things are happening on the screen at the same time my entire system lags to the point where I can't play the game. The FPS drops drastically and jumps up and down unpredictably, but even the UI feels like its going at 1fps.It lasts about 20 seconds and than everything returns to normal like nothing ever happened. I've never had it happened twice in one game even when I encounter a scenario where there are even more things happening on screen.

This has been a problem since ive built the PC and before I had overclocked or tweaked anything.
Since then I boosted the 2700x to 4125mhz with asus mobo software, used gigabyte software to boost the 2080, and enabled xmp profile for the ram, but I'm still having the same problem.

I'm an a newbie enthusiast, any help would be appreciated.

ROG Strix X-470-f Gaming
Amd Ryzen 2700x with stock cooler
16gb ripjaws V 3200mhz cas16
Gigabyte RTX 2080 OC Gaming
Samsung 860 EVO 1TB
thermaltake smart m series 850 bronze+ (Ive had it for about 6 years, light use for 4 years, been sitting around for last 2 years)
Coolermaster HAF X case (also 6 years old, everything running cool)