Did you monitor the temperature?
But this sound like unstable power supply. Is your charger keep on disconnecting?

Yes that's way over tolerable limit. (85c under load; and you have that at idle) You must clean up the fans, heat sink, and vents for cpu and gpu. In your case, normal thermal paste like mix-4 will do the job well. For better thermal performance, I suggest you use gelid gc-extreme.

As5 is a good paste, however it needs curing time; meaning they need time to reach optimal performance. In the case of as5, it's like 200 hours (it's stated in the as5 user manual; also take a look at the recommended way to apply it). Modern thermal pastes usually have no curing time. Just apply and that's it.

Basically you need a screw driver, a brush, a bottle of >90% alcohol, cotton/cotton butts, and thermal paste. It's better to do this outside of your house haha

You take off battery, press power button for a few secs to drain power; take off back cover, unplug fans cables; take off fans, heat sinks. Then starts cleaning up

edit: i have tried some thermal pastes, including as5, ic diamond, tuniq tx-4, mx-4, prolimatech pk-2 and 3, coolaboratory liquid ultra (clu), and gelid gc-extreme. to me i think gc-extreme is a better choice, because it has good results, and it doesn't leave anything behind (e.g. ic diamond is abrasive and it leaves black stain-like marks on the copper heat sink; clu is conductive, corrode aluminum, and is hard to remove)

 

You need to be glad that your processor hasn't fry... haha
It will auto shut down your laptop when it reach 105c.
So, must act fast to clean your laptop and repaste.

Directly go to GTX 970m la... 
If you want GTX 770m due to tight budget. I recommend you try out GTX 870m.
It is a very good card and running so damn cool