If there's a problem, it's most likely the GPU, but if you can't see the GPU, then you should check the options or maybe your graphics card doesn't have a sensor. What graphics card do you have? I've read that speedfan should show the GPU, but I don't know first hand because I use other programs (I've tried programs before that were meant to show the GPU, but for some reason only showed the CPU). I have pc wizard though (free) and that one shows the GPU.