Question Computer suddenly slow with no apparent sign of why, still slow after factory reset

[Zach214]

Problem: My computer Suddenly slowed down to a crawl, occasionally speeding up for a while before slowing back down. Games i could run before at 60+ fps are now down to 10-15. Web browsers are also much slower.

What I've tried: Complete factory reset, updating drivers, deleting unnecessary files, virus scans, checked temperatures of GPU and CPU (not overheating), reinstalled windows

My thoughts: I've had this computer for about 5 years, so it could have given up, but from what I've seen, it seem to be in decent health.

Specs-
MDB- MSI Z170A GAMING M7 (MS-7976)

CPU- Intel Core i5-6600K

GPU- AMD R9 390

SSD- SanDisk Ultra II 960GB

HDD- WD Black 5TB (2015)

RAM- G.SKILL Ripjaws V DDR4 3200 C18 2x8GB

 

[Ralston18]

PSU: make, model, wattage, age (5 years?), condition?

Power down, unplug, open the case.

Clean out dust and debris.

Reseat all cards, cables, RAM, and jumpers to ensure that all are fully and firmly in place.

Look in Reliability History for error codes, warnings, and even informational events that correspond with the time(s) of slowdowns.

Use Task Manager and Resource Monitor to observe system performance.

 

[Zach214]

PSU: make, model, wattage, age (5 years?), condition?

Power down, unplug, open the case.

Clean out dust and debris.

Reseat all cards, cables, RAM, and jumpers to ensure that all are fully and firmly in place.

Look in Reliability History for error codes, warnings, and even informational events that correspond with the time(s) of slowdowns.

Use Task Manager and Resource Monitor to observe system performance.

So sorry for the late response.

PSU- Rosewill Photon 1050w
Age-5 years
Condition- decent

I cleaned out the dust and reseated everything. It ran faster for a couple of hours but this morning it is back to where it was, so I'm not sure what happened.

I looked into reliability manager and there doesn't seem to be anything that is happening with the slowdowns (I've been having a problem with my computer crashing to a black screen for a while now, but that wasn't slowing my computer before and the times of the crashes don't seem to be relevant to the slowdowns) Reliability fluctuates between 4 and 1.

Nothing looks too out of the ordinary on Task Manager. the only thing is my usage of my GPU is a little lower than I would think it would run at.

Something I noticed was that when my computer is running correctly, there is a sort of high pitch buzzing sound (not 100% sure what its coming from, but it sounds like the GPU) and as soon as that buzzing stops, my computer slows down to snail speed.

Edit: The noise indicating faster performance sounds like hard-drive activity, but it sounds like its coming from the GPU/ Motherboard. the HDD activity LED doesn't seem to directly correlate with the sound