When my iMac (running 10.2.8 ) goes to sleep by itself using Energy Saver, the fan keeps running and doesn't shut down regardless of the time that goes by. When I put the computer to sleep using OA-Sleep, the fan does shut off. Is this normal? It seems like it should shut off in both instances to be truly energy efficient and to reduce wear and tear on the fan unit. Is something malfunctioning or is this normal?