It's possible there was a software/driver conflict. If it seems to have resolved itself after updating then I doubt it was hardware as it would still cause problems if it was.
Give it a few more days and make it work hard , play something super CPU/GPU intensive and see what it does.
If you want to see what may have happened hit the windows key + W and type in "event" then choose "View Event Logs" or something similar. It will allow you to view any events that occurred. This may help you nail down the issue.
Good luck !!
Link to directions for event viewer:
http://www.computerperformance.co.uk/win8/windows8-event-viewer.htm
ASUS G750JM+
32GB RAM / SAMSUNG EVO 1TB SSD / 1TB HDD / BD-RW
ESO / RIFT / NeverWinter / GuildWars 2 / Thief / NWN & NWN2 /
TITANFALL / BF 2-4 / UT2004 / Q4 / Crysis 1~3 / Dead Space 1~3