It sounds to me like your GPU is overheating the fan can only help so much. Your fan will run full speed from about 70c.
I suggest you load Hwinfo64 run the sensor and you will see your CPU & GPU Loads Temps and Fan Speeds. With this information you might see that the pasting on your GPU is or has failed.
I don't know of any fan profile programs that will work on a G75VX
Yes your temp are way to high and your fan speeds very slow? Under full CPU load mine run at 3800 RPM using burn in test my CPU never gets of 75C. The temps you stating your CPU and GPU would be Throttling to protect the hardware.
Repasting is not something to take lightly with notebooks. While a straight forward thing with desktops. It not impossible as many here in this forum have accomplished this. If mine goes bad I'll probably attempt it myself.
Most of the Custom dealers are repasting using IC diamond paste before you even get it from them. You might be able to get Asus to repaste or one of the custom dealers too? Shouldn't be too expensive for a shop that knows exactly what they are doing and have all the proper material and tools. I would search You Tube. There is one really great video on complete disassembly