Problems with Alienware Aurora r3

[1aussieonly]

Hey guys, I've been having some trouble for a while now with my desktop first of whenever i turned the computer on it would load up until
the windows logo then just go blank after that.
I tried safe mode and it wouldn't work either, then i was stupid enough to play around in the bios and all i got was blue screen, after that i
handed it in to get looked at and he fixed it but only for a little bit until it did the same thing again, i bought a new hdd with a new copy of windows 7 and i could log in finally.
But now whenever i play any game for more then a few minutes the computer just turns off and i have to unplug it from the power point and wait a while
otherwise it just starts beeping at me. I don't really have enough money to get it looked at again, any suggestions would be appreciated thanks. 

[jason2074]

Could be thermal events, power supply or game related problem. Do you see the problem by any programs other than games running? Did you try removing the side casing and also checking if the processor's thermal paste is intact or atleast replacing it? Just make sure the heatsink and fan are well in placed.