Computer shuts down when converting 4k footage

I have been having trouble on my 2012 MacBook Pro with 8GB ram a 2.3GHz Intel Core i7 and

NVIDIA GeForce GT 650M 1024MB

Intel HD Graphics 4000 1536 MB

graphics.

I am not able to import 4k footage and edit in Premiere, so created an ingest setting to make a proxy to work with a smaller file. Adobe support recommended also changing the renderer to the metal version which worked when I was on the phone with them, but each time I am importing footage and using Media Encoder to create the proxy, my computer screen just shuts off. Sometimes the entire system restarts and I get an Apple warning that there was an error that made the system shut down, and sometimes the screen just goes black, and the keyboard stays lit up. In that case I have to manually power down by pressing the power button until it shuts off. I send the reports to Apple when I restart the computer. Anyway, is it because my graphics card isn't strong enough? If I render the footage as 4k in Premiere once in the timeline, would it stop buffering so I could actually see what I am doing in real time? Please advise...