1st check Evebt Viewer in control panel in administrative tools and check for WHEA errors, error and critical errors. The best place for information when your computer shuts down and or crashes or even glitches a lot should throw some sort of log detailing what happened as in what part is failing and how. You need to be conscious of the time it crashes because the log file should have a time stamp within 1 minute of the crashing taking place. Full system build specs would also help a ton such as drivers installed and all the hardware.