This is a fan that sits on top of the cpu but the motherboard is not an Intel. I was cleaning all the dust out of the tower and the cpu fan was very dirty so I removed it so I could clean it better. When I tried to put it back the screws will not screw in. Why is this happening. They were screwed in when I removed it. I am so stressed out I can't think straight. I am also in school for tech support and a few weeks ago in class we removed a fan simular that sat on top of the cpu and was able to put it back without any problems. Please help me as I can't let this computer go unused. My husband uses it and I really don't want anyone using the one I am using to write to you. I just don't know what to do. Please help.