Sounds to me like ram, psu, or storage. Need to test that psu. Just unhook that sata drive too. Storage i assume. bsods aren't doing it any good, and it will help eliminate storage as an issue. I see you've done sfc, but what about a chkdsk /f ? Does it scan clean or find errors?
Temps are good?
Yes, as far as I can tell and have checked temps are all good.
I don't believe it's the hard drive's issue since it has only been used for storage of files and nothing else and it was also used on my previous system on which I never had a BSOD issue.
Regarding chkdsk /f command I remember trying it but not being able to run it because I was getting a message about NTFS system something like that.
I just quickly rebuilt everything, checked psu cables and stuff to see if there is any visible damage, took out and in again ram sticks, gpu, cpu cooler, refreshed paste, only thing I did not take out is cpu and sys fans but they are not connected to mobo, they go to an adapter of the case that takes power directly from psu.
So I connected only, keyboard, mouse, ethernet and only the Dell QHD monitor to gpu through display port for now and there is no crash yet. I will just wait to see if anything happens with the system like this just so I can make sure there is no peripheral issue, or more than one monitor issue and go on from there.
I am currently on this stage still. Around 3-4 days have passed, PC is currently being used for normal office work and a little gaming and I still have no crashes yet.
I will go on like this for a while and try to stress system a little more and after a few days I will connect the second display monitor, which I think will be the biggest test to see if crashes return.
If BSOD never appear again after connecting the monitor and rest of peripherals, I will probably assume that the fix was one of the removal - putting back on of one of the pieces mentioned above, with RAM being the most probable.
However, I am not very optimistic, I believe that crashes will return after I connect second monitor, so I will update as soon as I proceed.