In brief I custom build computers for resale and I have had 2 customers report restart issue since the beginning of January 2018.
You can rule out overheating problems and specific graphics card problems as the 2 computers I built have different cards (Nvidia & AMD).
Both computers use AMD FX Processors but the models are different. They both use the same ASUS Motherboard.
OK lets be clear on one thing. These customers have used the computers without problem since 2015. The only common denominator would be a Microsoft update on Windows 10 build 1709.
Build 1709 has produced many problems with AMD 3000 Motherboard based chipsets resulting in a 3rd party GPU having to be installed. Whilst this has resolved the problem, you still need to prevent Windows from updating the GPU driver as this will once again
result in low resolution and other issues.
The one thing that is common to each of these restart problems is the System Error Log. You will see an unexpected shutdown closely followed by Error WHEA-Logger.....AMD Northbridge Machine Check. I am not sufficiently qualified to give a reason for this
error however, I have shared this information with others in the industry.
I take no credit for what may be a 'resolution'. I am currently trying this with one of the customers and I await the results. Another custom builder has suggested that it may be due to an auto restart following System Failure. Under normal circumstances,
a Blue Screen Of Death (BSOD) would result in a debug log being created following an automatic restart. It is believed that this failure bypasses the BSOD and just restarts the system.
Possible resolution as follows : Run SystemPropertiesAdvanced.exe. Go to start up and Recovery Settings. Remove Tick from 'System Failure' Automatically Restart.
I cannot help but think this problem is linked to the onboard AMD 3000 Chipset issue that initially occurred following a Microsoft AMD Driver update in December 2017.