Reply to G-CPTN
This could be an overheating problem. How old is the Lap top and has it had a spring clean ? At this stage its best to look at the obvious rather than a component/Windows 8 problem especially if its been working without problems for the last few years.
There are lots of sites that give access to advice in situations like this and you may even be able to find advice relating to your particular Lap Top.
CAT III