I’m trying to render a video that contains clips from fairly large source files (around an hour each), and at around one third of the way the rendering causes my whole system to shut down! Scary stuff…
Any ideas? I am on Windows 8, AMD 6 core processor and plenty of RAM and hard drive space.
Check Windows error logs and see if there’s a clue as to why.
Could be an overheating CPU or GPU…
Will do when I get home.
Ok, I’ve been reading through the logs, and all there is is an after the fact message thus:
“The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.”
Try turning off the GPU while rendering.
Thank you all for your suggestions!
I located the issue to the CPU overheating, and have since cleaned the fan and added additional zink paste. For now it’s working again, but I suspect I need to purchase a new fan before long. 
Never add thermal compound. More isn’t better. Less is.
Clean the old thermal paste off the CPU and heatsink (WD40 dissolves it well) then apply new fresh thermal compound.
AMD recommends to squeeze a pea-sized amount onto the center of the CPU. This should be evenly spread over the entire processor surface area, and you can use a credit card as a tool to help accomplish this task. Keep in mind that the purpose of thermal compound is to compensate for imperfections between the CPU and cooling block, not to add a barrier between them. A proper application should result in a very thin layer without any visible streaks or clumps
Hey, I was in same situation, computer was shutting down while I was rendering videos in Adobe premiere pro or Sony Vegas pro. Found a way to control power and cooling supply to processor while on power saver+ affinity setting of core! Hope this helped someone!
Fixed - Shutdown while Video Rendering | Video Game - YouTube