Question Why is my PC Freezing?

My PSU is a hk380-12gp. I run a HDD, a Hitachi HCS5C3232SLA380 290gb. My CPU average temp is 46 c to 48c, and my GPU runs at 29 c to 30 c. My ram usage is around 70-71% and my HDD runs at 80-90% when I'm gaming.
 
I actually bought this pc off of someone last Christmas, windows runs fine until I start playing Fortnite. I play numerous other games but Fortnite it the only game I stutter in.
 
It came factory reset.
Download and run Adwcleaner: https://www.malwarebytes.com/adwcleaner/
Delete and quarantine everything it finds.

If it doesn't find anything, then I'll be convinced it actually is factory reset.
That drive usage is pretty high, considering your ram isn't maxing out yet; when the ram does max out, the system will then write temporary files to the drive.