I have had this happend to me twice, I have the x51 r2 with amd radeon r9 270x and well the only difference is I do not get a error message. Its only happened to me while playing raceroom experience,

First I get my TV saying no signal but the x51 is still on, then like 10 seconds later it shuts down all the lights turn off then for a second they all come back on then the unit completely shuts down. Then I push the power button and it starts right up but I do not get any error messages. Any advise/help would be appreciated