Gaming Laptop Suddenly Shuddering on Games (MSI Apache 62 Pro)

Hi, I'm actually posting for a non-redditor pal because I've exhausted the breadth of my knowledge.

Around three days ago his laptop began shuddering and experiencing graphical lag while gaming. At first I thought it was a poor connection issue as it was happening in Overwatch but it turns out it's afflicting all his games. Fallout 4 slows to a crawl, like watching a power point be clicked through.

I didn't find the right solution from the Internet.

References:
http://www.debate.org/forums/miscellaneous/topic/101409/

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