All right /wsr/, I'm having computer problems. Can you help

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All right /wsr/, I'm having computer problems. Can you help me identify and fix it?

Whenever I play Dota 2 (I am not sure if this applies to other games, Dota 2 is the only one it has occured with. I can confirm LISA worked fine), my computer crashes without a bluescreen or error message and then immediately restarts. After restarting, there's no error message either. Like nothing happened. I've only seen it happen while playing Dota 2.
I've tried identifying it on my own, but it hasn't worked. Here's what I've suspected:
It may be a RAM issue. I had some issues with this a while ago (something on the bluescreen about errors in paged file areas not being available) , and first fix that worked that didn't require replacing them is what I went with: I removed the paging file. This works for me, I haven't had many problems but I have to watch my RAM usage carefully, but I'm used to that having only 4 GB.
I thought it was an overheating issue as during play my GPU reached temperatures of 82*c peak, and then shortly crashed. After fixing this and lowering the peak temperatures to about 75, it's still occurring though, and I don't think a GPU crash and kill the entire computer.
While attempting to fix this through the magical process of fucking google it, I came across some anecdote that a dusty mobo could be the cause. It's been a long time since I last dusted it off, so this may be the cause, but I don't know if a dusty mobo can actually fuck things up that much, and I'm sure it can't be too dusty.
Here's my idle temperatures. I don't have any under load screenshots, though I could get one if necessary.

Any ideas? I'll reply with anything I can come up with or anything you need to help fix.