A clean, dust-free PC will help your machine perform to its topnotch performance. As time passed by, no matter how clean is your house and even if you always cover your unit with a dustcover, little by little, dust will accumulate inside. Dusting off is necessary, one way to know that you need to clean up is by listening the fan of your PC, if it becomes too noisy, dirt is most probably settling in and you need to dust it off.