Computer reboots during games

While playing video games the computer will go black screen and shut off, and then reboot. Always when it reboots it sounds the like fans are working very hard as it makes all this fan noise, but this is only temporary. Once the windows logo is in the screen, the fan sound is gone and the computer functions as usual. I've had this issue numerous times and I've checked event viewer, it's always the same: Event 41, Kernel-Power.

Here is the Microsoft page on this issue: http://support.microsoft.com/kb/2028504

It seems that my issue most closely resembles scenario 3 here, without the hard hang as the computer simply goes black screen and reboots.

I've had notorious RAM issues in the past and I am always first to blame my computer problems on that. I've already replaced the RAM on this rig once and but I'm beginning to think it might be something else. I also tested the RAM with windows RAM test however I have not tried Memtest86.

So I just recently DL'ed and tried Furmark the GPU Stress Utility, after running this program for about 5-10 minutes it will crash it to black screen just like in video games. Is it possible my computer isn't getting enough power?

I also checked some more obvious things like dust in the case, fans etc. I've checked my CPU temps during stress tests and video games it stays around 30-40c. My CPU and GPU fan both are working fine.

I also checked around forums and read somewhere that you can have conflicting audio drivers and that can cause this crash I tried disabling all of them and have found it to crash in every possible configuration.

Thanks for reading my post, if you guys need any more information crash dumps/screenshots or otherwise please inform me how to upload them as I'm not too knowledgeable on these things.
Edited by Thunderhorse761 - 8/2/12 at 11:06pm

Added my rig to my sig.

*EDIT* Also my most recent upgrade was my current RAM, which I replaced because I was having constant blue screens with my old RAM.
And during Furmark's most intense testing my GPU temp got up to 87c.

The first time I had this issue was 3/11/2012 according to event viewer.
Edited by Thunderhorse761 - 8/2/12 at 11:20pm

Here is the exact name.
RAIDMAX QUANTUM RX-700

Here it is on Newegg.
http://www.newegg.com/Product/Product.aspx?Item=N82E16817152033

This is the oldest piece of hardware I have in my computer and the only piece I didn't upgrade from my old rig. I've had it since 5/6/2008.
Edited by Thunderhorse761 - 8/2/12 at 11:26pm

Actaully it did crash, about 5 minutes later in a weaker test. I stopped it at 87c because I didn't want it to get to 90 degrees.

Also I will run a mem test soon, do you recommend memtest86?