WFlashKiNGwould be good to know what i7 it is, and if you have overclocked itCan't remember all the details of the processor right now but I know i've never overclocked it.
As I wrote down all the specs above off the top of my head, I made a mistake about the CPU. It's actually an Intel Core i7 3770 3.4GHz. Sorry about that.
StevieDoes your PC Freeze before this happens?
Is it heat?
I use to have this problem with my pc a year ago, due to it overheating and the cpu fan controller being plugged into the wrong socket.
More unlikely of a case, the same pc actually died recently, due to again the CPU, from this long period of time with my computer crashing, and me choosing not to take any action.
TLDR: Just make sure your computer isn't overheating.
Nope, it doesn't freeze or do anything special; it just shuts down by itself (to clarify: when this happens the PC doesn't show the "turn off" screen as when you select it from the start menu, the case just powers off and the monitor goes to black).
I ran speedfan to check the temperatures, and they seem normal. I recently (like a couple of weeks more or less) cleaned the dust from inside the computer too.