What is RTSS (you get it installed MSI Afterburner) telling you about your loads when the game is running?
You should set it/afterburner to show the following in the overlay:
- Average FPS
- CPU Clock
- CPU Temp
- CPU Usage
- RAM Used in MB
- Memory Used Percentage
- Show every CPU thread's percentage load
- GPU Temp
- GPU Usage Percentage
- GPU Clock
Disable any other overlay options (example, the GPU settings for power %, power, power limit, voltage limit, load limit) as GPU monitoring has been said to cause performance issues.
This video is a tutorial on doing this:
https://www.youtube.com/watch?v=_KQCcwP2mro
There's a portal experience called "Mark De Bench". Load it, then spawn and stand on the tyres to the right of the spawn. Don't run through the map, just stay on the tyres.
After a few minutes take some pictures of the overlay (using steam screenshots or even just on your phone) so you can post to show us what your CPU & GPU and Memory load is in-game along with the FPS.
You may also want to consider formatting the PC and installing a fresh OS, while also resetting your BIOS clean and setting them both up from factory settings. I would also consider buying a 2 x 16gb stick of fast ram like Corsair CMK32GX4M2E3200C16, Silicon Power SP032GXLZU320BDAJ7 or SP032GXLZU320BDA, G Skill F4-4000C18D-32GTZR or F4-3200C16D-32GTZ.
Keep all your CPU cores enabled, leave HAGS and DX 12 disabled and don't use a framecap.
If it's still failing after that you likely have a hardware fault.
