Sudden frame drops

So I built my computer about a year ago, games such as assassins creed origins, modern warfare, and even cyberpunk ran fine. I've been playing final fantasy 14 for a few months, it runs perfectly fine, then suddenly at the last cutscene of shadowbringers it decides to drop a few frames, then a while later I do a few bosses and framerate decides to drop mid boss. these frame drops are entirely random and seem to mostly happen on Final fantasy 14 and doom eternal from what I have seen so far. I tried modern warfare (with RTX) and forza and they work fine. any help is much appreciated!
build is
OS- windows 10 pro
CPU- AMD ryzen 5 3600x
16gb ram
Mobo- Micro-Star International Co. Ltd B450-A PRO MAX
GPU- Geforce RTX 2060 super (msi)

to specify how random these drops are- I'll stand in an area for about 10 mins, it will run at a solid 144, then suddenly drop to 15, then it will be inconstant for a while, after standing still and doing nothing for 10 mins.
That's a hard one...corrupted game files perhaps? Using a spinning hard drive on this rig?
I'm using two SSD's. I uninstalled the game and reinstalled on the other. that didnt help, but I took out my GPU and gave it a bit of a cleaning and so far so good.