PC crashes while gaming

[PhantomScore971]

My setup:
cpu: amd athlin x4 760k 3.8GHZ
gpu: MSI gtx 660 oc twin frozer edition
mobo: asrock fm2a55m-vg3+
ram G-skill ripjaws 2x4gb
psu corsair 620 W
windows 7 ultimate 64 bit

cpu is water cooled.

so when i stress test my rig it doesn't crashes but when i play a game ( any game) it shuts down and does not reboot but fans, cooling and lights stay on. the pc is not overheating temperatures read by speedfan.

please help me

 

[kamhagh]

what stress test cpu or gpu or ect... or all?

thats weird !!!

you mean only display stays off?

might be a driver problem !!!!

 

[PhantomScore971]

for testing i used prime95 and furmark
i uninstalled and re-installed the drive 4 times and no change and according to windows the gpu is functioning correctly.
its really the system shutting down it just stops working except for the fans and lights.

 

[kamhagh]

that might be the screen just turning off, i have no idea!, i would just try ctrl-alt-del so i might maybe get somewhere !!

wait for other peoples answer :|

i GUESS ram can make computer go like this too, or it will only give blue screen if its faulty!

as i know some gpus do some stuff when they detect Futuremark ! so i would try 3dmrak if i had it!!

 

[PhantomScore971]

correction: the pc is rebooting. Could it be that the PSU is lacking, not enough power, too old?