Have you updated to the Anniversary Update yet (build 14393)?
IMO that would be the first step - and would help to validate that Windows isn't the problem.
Don't worry about the Creators Update yet - Microsoft suggests waiting for Windows Update to install it.
The Admin log doesn't show errors in the period just before the shutdowns.
As such, this is most likely an error that Windows can't see.
While it's most often a hardware problem, it can also be due to compatibility issues or problems with low-level drivers.
Most often, a sudden restart like you describe is also due to a hardware problem, although it could be caused by a misbehaving program.
To tell which, check the error reports (both in the WER section of the MSINFO32 report and the Admin log file from Event Viewer)
The absence of errors is usually a sign of a hardware problem
Just because you monitor your temps doesn't mean that a component inside the system isn't overheating.
The temp sensors just monitor a few components - not all of them.
IMO tho', this is less likely than a hardware problem not involving overheating.
As hardware becomes more complicated (and the software that supports it becomes more complicated also) - diagnosing hardware problems has become more difficult
To rule out the Windows problems that you suspect, there are several things that you can try.
Start with these free hardware diagnostics: http://www.carrona.org/hwdiag/html
Please run ALL of the tests and let us know the results.