computer powers off and restarts when running a game that is demanding.

[alexk1212]

I have a constant problem of that when the computer is being demanded upon to work hard when running an intensive game.

To try to prevent this I have recently purchased an 850w power supply as I originally had a 700w in the computer although this does not seem to have had an affect.

my pc build is:
asus z87 - k motherboard
intel core I5 - 3.4MHz - standard fan cooling
2 X 4gb 1866MHz RAM
NVidia gtx 780 2GB graphics card
2 X 1TB HHD
850W psu gold plus

 

[Blas]

You should check the temperatures. As you say it happens when you put heavy loads on the GPU (and possibly CPU too), temps might be the culprit. Use CoreTemp to check the CPU's and GPU-z for the GPU. Launch a game, and check the readings. Or have them log to a file (both have the option). If you see very high temps, above 80 degrees Celsius, that might be it. You would then need to see why the coolers are not doing their work, but let's first check the temps, and let us know how it went.