PC Freezing while Gaming/Graphic Design/Coding

[Invecteris]

Hey Guys, 

Since a couple of weeks now i had these Freezes and im kinda at the Point where i dont know what Solutions i could try anymore. The thing thats happening. While im playing with my Pc or working on Graphics stuff my Screen freezes after around 1-3 Hours. Screen Freezes completely Fans are still running and sometimes my Mouse and Keyboard go dark sometimes not.

Things i changed that i thought could have caused it: I Changed my graphics card i upgraded my gtx970 to an rtx 3070. I Upgraded from win7 to win10 and i Upgraded my PSU. 
Specs: 

Intel I7-6700

32GB Ballistix DDR4 RAM

Asus Tuf Gaming RTX3070

BeQuiet 850W PSU

MoBo:GA-Z170-HD3P

 

Stuff i tried so far: Cleaned the Registry, cleaned the PC, Used DDU and installed fresh graphics driver, Updated the BIOS, Updated the Chipset drivers, Deactivated Background apps, Changed the Pagefile my SSD and HDD can use. 

 

Maybe someone has an Idea for Context im not Overclocking and the Temperature Protocolls are not out of the ordinary. Im not an expert when it comes to PCs so i take every help i can get.  Thanks in Advance.