The GPU cooling system of the M6600 and M6700 is better than that of the M6800, It has 3 copper bars instead of 2 like the M6800. I don't know what your fan speed, but for my M6800, it reaches 4500-4900 RPM and I also use liquid metal thermal. If the GPU temperature is too high, you can use Dell Fan Manager and run the GPU fan at maximum speed.. I'm still trying to modify the vBIOS for the P4000 on the M6800, hoping for results soon. A while back, I used the P3000 and was the first to overclock it to almost the default P4000. But at that time, my family went through a financial crisis and I had to sell my laptop. I didn't have the mental space for anything else and didn't want to back up the overclocked vBIOS of the P3000.