jonjsilves :
http://www.corsair.com/en-us/hx-series-hx750-power-supply-750-watt-80-plus-gold-certified-modular-psu
Whoops, my bad...you already said that before. Now I'm really confused to what the problem it is.
Do this now. I did this before and it worked for when my computer had an error with dump files.
Try redoing the instance of playing games and waiting for your computer to crash and shut down. Take note of the exact time it shut down. Then AFTER it shuts down, go into windows, and once you get to the desktop, hit the shortcut "windows button+r"
Something called Run will come up and most likely on the bottom left of the screen.
Type in "eventvwr" (without the quotation marks)
Even viewer will pop up.
On the left pane there will be a section called windows logs UNDER "Event Viewer (local)"
Click on it, and then click/double click "System"
To make the process faster, go on "filter current log" on the right pane and check warnings, erros, and criticals.
Here you will see the many events that your computer ran through, What you are looking for is "error" and "warning" before and after a big X for critical.
With the time you noted for shut down, look for a CRITICAL at that time, usually looking like this:
"The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly."
Then see what errors came before the shut-down CRITICAL statement. Additionally you can look for WARNINGS but usually these are things that the computer just puts there as an extra note and doesn't see as to crucially affecting it.
Some times this method is useful for the purpose where you don't know why your system shut down and even though it is usually for software, the errors can be related to hardware for sure.
P.S. Sometimes you can get Warnings through the event viewer that says things like:
"Whatever driver was detected. This filter has not been certified by Microsoft and may cause system instability."
Look for those kinds of warnings as well.