Atrocious frame timings on my PC as of recent.

[DeathlySalt]

Hi,
Lately my computer has been having atrocious frame timings, varying incredibly wildly. I've tried tons of different things to see if I can figure out what's going on, but I've had no luck. The stutter is so bad it has actually made multiple games unplayable. Not sure what to do here. Any help would be appreciated. Thanks!