Dust acts like a blanket that keeps the PCB warm, contributing to the possibility of overheating. The PCB and heatsinks, fans, case interior and so on should be cleaned regularly. Take this opportunity to clean the board.

Use an anti-static brush. Do not use any brush, for most brushes will cause static charge to build up and can damage the electronic components. Compressed air is also useful, especially for cleaning out the CPU heatsink.