Computer running slow at Wellesbourne in Warwickshire

This morning we are at Wellesbourne in Warwickshire repairing a desktop computer that is running slow one issue that may occur here is that if the fan on the processor is pulling the air towards the heat-sink there will be a large deposit on it which will increase the heat and then the processor will shut down sections of the processor in case of failure. This one has a bit of a carpet on the processors heat sink but the main issue has been caused by some malware which we removed by editing the registry and running a Malwarebytes scan