Computer Turns Off When Playing Games

I am having an issue with my computer turning off while playing games.

Everything else works just fine, but when i boot a game up it will play for a few minutes usually and then the entire computer just shuts off.

I am sure air flow isn't a problem because i have sufficient fans :/

Sorry if some specs are missing as I'm a newb. Just let me know if you need more info and I will do my best!

Windows 7 (build 7600) 64bit
Intel(R) Core(TM)2 Quad CPU Q8200 @ 2.33GHz
NVIDIA GeForce 9800 GT 512Mb
Memory : 4gb
PSU 500w

Also have a cooler master cpu cooler attatched

Thanks for any help you can give, guys!

Also, I don't know what help this may be but sometimes I can turn the computer back on right away. and sometimes I will have to wait a few minutes before booting up again

 

What you describe does suggest a heat issue even though you believe you have enough fans. I suggest running GPU-Z to monitor your graphics temperature before shutdown: http://majorgeeks.com/GPU-Z_d5796.html

Have you looked at the Windows event log to see what events are recorded at the time of shutdown - report these back here.

 

This supports the heat theory.

What motherboard do you have? My main gaming rig was acting just as if it was over-heating a couple of months ago, and it turns out it had a serious BIOS glitch. Basically, when my CPU hit 65C, the BIOS thought the CPU was actually at 95C, and in panic shut off the whole system. Very annoying. BIOS update fixed my issue...

...it might not fix yours, but taking a look at the motherboard never hurts.

 

The last temperature reading from the gpu was at 67 degrees before the shutdown.

I opened the event log, but I must admit that I am unaware of what to look for. From what section should I pull data?:confused

Also, my motherboard is a Gigabyte EP43-UDL, hope that is a help

 

Look under system events and look for errors or warnings at the time of shutdown. Similarly look under application events.

Have you looked at the computer manufacturer's website for BIOS updates for your motherboard?

Also, check the device manager http://windows.microsoft.com/en-US/windows-vista/Open-Device-Manager to see if there are any exclamation marks against dvices.

 

Ok, here is the text file from speccy.

Also, I will run a game a little later today and when it shuts down, I will post the results of the event viewer.
Everything was fine in the device manager if I recall correctly after a couple days.

I appreciate the help you guys are giving me.
Hope we are one step closer

 

I just had another shutdown, but I'm a little confused as to just how, and particularly which Event Viewer logs I should save. :confused

Also, is there a program you would recommend to log those temperatures at the time of shut down?

As for the case, it is a NZXT Lexa S.

There are two 120mm intake fans, one on the front-bottom of the the case and another on the side of of the case. There are also two 140mm exhaust fans on top, as well as another 120mm exhaust on the top-back of the case. Also, there is a 120mm fan on the cpu cooler, but I don't know if that counts or not.

Thanks again for the help thus far