I have a MSI GE60 0ND laptop with a GTX 660M GPU. When I play games like Minecraft or Portal 2, the core clock is stable at 835 MHz. Recently I tried to overclock it using MSI Afterburner but it wouldn't let me change the voltages or the clock speed no matter what I tried. Various Google searches yielded solutions that all didn't work. Is there any way I can overclock the GPU? Further Info: I have the nVIDIA 310.70 drivers and Windows 8.