Gateway p7811 fx

Hello, I have recently bought this laptop an have encountered a problem.
When I run 3dmark 06 or furmark after about 3 minutes the computer screen goes black and freezes every time I run something graphically demanding. I have stripped the computer to the bare bones and cleaned and reapplied quality thermal paste to the gpu and cpu to make sure there are no problems there and cleaned fins. The gpu for some reason idles around 65 c fan kicks in now and again and doesn't go above 78 c on testing. When on furmark it reaches around 78 c and the fan kicks in hard, brings the temp back down to around 70 c and after a few minutes the system completely crashes. I have the latest bios 93.23.00 from the gateway official site and video Bios is 62.94.37.00.13 which I DID not install the privious owner must have or is the original.
I have all of the latest nvidia drivers and system tools installed with windows 7 ultimate all seems to be working perfectly.
I have run memtestg80 with no errors.
Please can some one help me with this problem im thinking it may be worth flashing the video bios to the latest version but where can I find a download and how is this done?
Many Thanks to any information

 

I've just downgraded my bios to 9c.17 and the Gpu is a lot cooler but still freezes after several minutes?

 

Does anyone have the under volt bios mod available to download?

 

Tried to NVFlash the undervolt mod and back up the original bios in dos and and I get and error eeprom not supported how do I get arouund this??

 

So no body can help me with this topic????
Bump !!!!

 

not too many of us are on the modded bios. the usual for lockup for these is the 2D-3D memory speed switch over. For myself, in the p7805, the cure was to use powermizer off, allbeit I rarely ever had an issue..............