What you need to do (although I think you might not want to do this) is to pull of the cooling unit off of your GPU. This will open up the picture of the GPU board and probably show you where the connection is on the GPU that your looking for. There are several Youtube videos out there that show you how to install your cooler that do show where the connection is being done on the GPU. If you can't find the connection onto the GPU, you will need to remove the cooler (because it isn't doing you much good right now) and find where your connection point is. This connection controls and allows the fans to turn on for the GPU, under whichever conditions that the GPU requests it to do.