Windows 10: Pc screen freezes then shows little green box then turns completely black

I've been using this free editing software called Davinci Resolve and have been messing around with the Fusion Tab that is basically after effects just now my pc froze couldn't move my mouse anything, then it showed a black screen with a random green box in it then after a few seconds my monitor tried refreshing i know this because my monitor showed the HDMI text on my screen screen just showed a completely black screen. Need help with thisHere are my specs

:)

 

black screen with green box in it

When I stream videos online I get a black screen with a green box in it.on mu Lumia 535.

 

computer screen turns black after it shows preparing automatic repair

it shows that for about 5 seconds and then the screen turns black With a white foggy bit

 

New laptop hardlock with black screen

I have a new notebook, running Windows 10 Fall Creators Update, which is randomly freezing, showing a black screen. System specs:

• intel core i5
• HD is an SDD, 250GB
• GPU: Intel HD graphics 620

Symptoms:

• happens randomly, related to no particular reason, time of the day, and programs running
• when freezes, the notebook screen is "active" (back light is on) but completely black; external monitor, connected via HDMI, is black as well
• when freezes, no key input is responding. I tried to press "CAPS Lock", which has a led on it, and the led is not toggling
• I noticed I can keep the PC on for several days, without any problem. It always freezes whenever I'm actively using it

What I already tried:

• reinstall Windows from scratch (even starting from an external USB drive)
• run windows in "clean boot" mode (all non-MS services disabled, all startup programs disabled)
• update the BIOS, and all "relevant" drivers (GPU, System Firmware, network interface, bluetooth, ...) of the PC to the latest version
• testing the memory with MemTest86+: no issues, after several steps
• stressing the GPU with FurMark: reached quite an high temperature (70°), but no issues
• stressing the CPU with IntelBurnTest: reached quite an high temperature (70°), but no issues

Now, I would guess it's an hardware problem, but the strange thing is that we ordered 6 identical PCs, and this is happening on 4 of them. Therefore, for "statistical" reasons, we don't think it could be possible that all of them shows an HW issue... It only happens with a different rate from one PC to another (for instance, happens daily on my PC, and once a week on another)
Any idea on how to investigate this issue further?
Any test / improvement I can do?