I have an iMac about 5 years old that I want to give to my mom. It has developed a temp sensor issue which makes the fan run now and then when it doesn't need to, but it still operates perfectly otherwise. I want to give it to her clean. It has Snow Leopard installed but it did not come with that. I can't remember what it had originally. Can I just do a clean reinstall of Snow or is it best to restore it to factory settings, then install Snow? And I'm sure hoping any install will be successful with the sensor issue!