PC freezes after being left idle for a few hours

I've been having the exact same issue as described in this thread. I hope the CAM software gets an update to address this soon. I just turned off my CAM software today after having this issue since updating to the 20H2 update back in September. I had no issues prior to 20H2. I too also thought it was a GPU issue due to having 3 monitors hooked up to my graphics card, but I don't have any way of testing that. It wasn't until today that I noticed that it seemed to be crashing primarily when engaging with the PC after it had been idling for a little bit (even when it's playing YouTube video's). Stumbled on this thread when searching that specific symptom. 

old

Ryzen 5 - 2600

Gigabyte B450 Pro wifi

GTX 1660ti - 6GB

16GB RAM

NZXT H500i case with CAM hub and CAM software. 

I just upgraded my CPU and MOBO last week hoping that would solve my issue. That did not solve my issue (also did a fresh install then as well). I also tried changing out the RAM in December and that didn't help either.  I also tried 2 clean installs over the course of a couple months and rolling back display drivers and not using GeForce game ready drivers -  made the mistake of doing a fresh install before trying to roll back the update when I did it in September so I couldn't roll back to the previous version of Windows - but none of that helped. . 

current

Ryzen 7 5800x

Asus B550 Gaming F

GTX 1660ti - 6GB

64GB RAM

NZXT H500i case with CAM hub and CAM software. 

I'm very grateful for all the work that everyone has put into this thread! Seriously hoping that this issue will no longer haunt my dreams. 

UPDATE:

3 months have passed and I have not had a single crash.

All I had to do was disable the NZXT CAM software that I was using to control my RGB hub.

Had the exact same symptoms as OP ever since i upgraded from a Ryzen 7 1700 to a 3700x on a Asus Crosshair VI Hero. Tried pretty much everything the internet suggested although i dont even use Corsair Link or NZXT CAM, i've been using the old Aura Sync to control my RGB. 

For the people still searching for a solution, try to disable Global C-state control in the BIOS: 

I tried that as a last effort before returning the processor back but after1 week of use i have yet to experience a "freeze" with the C-state Control disabled. 

I will report back in case i get another freeze but so far it seemed to solve my "freezing" problem.

This solved my problem! Went into BIOS and disabled C-State. Computer has not froze for 2 weeks since making the change. Good luck to all! Thank you so much, @McK-4268!

I couldn't believe this is what was causing the issue, but since I've disabled NZXT CAM from startup I haven't run into any of these weird crashes (for the first time in more than 3 months!). It even worked fine once when I had to open it to adjust some lighting before closing it again (I made sure to end the process completely afterwards). Thank you so much for the tip, it's unbelievable that this might've been what was causing the freezes.

So heres an update, at first I thought it was faulty hardware as I had a failing hdd, I replaced it but the issue seemed to persist, then I suspected it was Wallpaper engine.

I got dual monitors, but the first one is a 16:9 and the second one is an ultrawide 21:9 in portrait mode, which means the screens make an L shape. In Wallpaper engine I had it set to 1 wallpaper spread across both monitors instead of one wallpaper per monitor, did this to have some flow between the two, but I think with the weird resolution of 3000x2560 it causes some weird bug with the GPU drivers and it eventually locks up. What made me realize this is that whenever I move my mouse over to the second screen, Nvidia shadowplay  glitches for a few seconds and turns off because it cant seem to handle this weird resolution as it wants to include the second screen im working on.

Because Wallpaper engine directly effects the desktop i think its what leads to the entire windows system locking up.

This is what was effecting me, yours may be slightly different for example I saw people saying NZXT Cam may be the issue aswell, but for me this is what caused it, setting 1 wallpaper per display instead of making wallpaper engine treat it as 1 fixed the issue for me.