Thermal Management in Fanless Industrial PCs: How Passive Cooling Works

How Passive Cooling Works in Fanless PCs

In a fanless industrial PC, processor heat travels through a thermal interface material (TIM) to a copper or aluminium spreader plate, through heat pipes (in some designs) to the chassis walls, and then radiates and convects from the outer surface to the surrounding air. The entire chassis acts as a heatsink — external fins on the top and sides maximise surface area for heat dissipation.

TDP: The Critical Design Limit

Every fanless chassis has a maximum TDP (Thermal Design Power) rating — typically 15W, 25W, 35W, 45W, or 65W. The processor's TDP must not exceed the chassis rating, otherwise the processor will thermally throttle (reduce clock speed to reduce heat output) or, in extreme cases, trigger a thermal shutdown. Always match your processor TDP to the chassis specification.

Effect of Ambient Temperature

Passive cooling efficiency decreases as ambient temperature increases — there is less temperature differential between the chassis surface and the surrounding air. A fanless PC rated to 60°C ambient with a 35W processor may only be rated to 45°C with a 45W processor. Always check the thermal derating curves in the product datasheet.

Installation Best Practices

• Allow airflow around the chassis — do not install directly against a wall or inside a sealed enclosure without ventilation provisions
• Avoid stacking — do not stack multiple fanless PCs without spacing for heat dissipation
• Monitor ambient temperature — if control panel temperatures exceed rated ambient, add forced air cooling to the enclosure (not the PC itself)
• Orient fins correctly — if the chassis has fins, orient them vertically for maximum natural convection