Sounds like the system may actually be producing a blue screen error and then spontaneously rebooting as a result of the check box located here (see attachment).
Type
advanced system settings
into the search box and hit enter and uncheck the box.
Check the C:\windows\minidump folder for files with the .dmp file extension. Then read the following sticky posts in the root of the BSOD forum as they apply to getting help on BSODs.
Link Removed make sure to follow the instruction regarding right click->run as administrator.
Link Removed make sure to follow the instructions regarding all SPD tabs for CPUz and zipping up the the exported HTML report from RAMMon.
Link Removed
Keep us posted and
Welcome to the forums.
Regards...