Question System running sluggishly after an hour or so.

[Reah]

My system is in Signature
This is a fairly new System, but after I have been doing anything for an hour or so the entire system slows down, games lose frames.
I click on the start menu and there is a pause, I get lag when typing, everything just seems to slow down, If I reboot the pc it will be back to working fine for about an hour, then it does it again,
any clue what would cause this
Thank you for any advice in advance.
Reah
Windows 10
Ryzen 7 3700x running at 4ghz
16gb Gskil 3600 running at 3800
Radeon RX 5700XT
WD Blue 1Tb SSD as C drive
500gb Nvme m.2
1Tb HDD
3Tb HDD

 

[sizzling]

Signatures don’t display on many devices and some members switch them off so they don’t see them. I recommend you add the details to your first post.

 

[Reah]

Updated post with system info at the bottom