Fan and Heat Sink Failures

• If the bearings or blades of the heat-dissipating fan built into a GPU fail, the card will overheat. A GPU heat sink won't work if the thermal conduction between it and the card is compromised.
  
  

Dust and Other Contaminants

• Computers fail in dusty or smoky environments because contaminants build up inside their cases and disrupt airflow or heat dissipation. These contaminants act like an insulating blanket on cards and drives.
  
  

Poor Case Design or Selection

• A computer case must be designed to provide sufficient airflow for component ventilation. A badly designed case, or one that's not rated to house the components installed in it, can lead to heat-related failure of graphics cards and other components.