PSU Fan Direction: Up vs. Down Positioning
Which way should your PSU face? This guide explains airflow direction, dust considerations, and PC case compatibility details.
How PSU Fan Airflow Works
The large fan on the power supply is an intake. It draws cold air into the PSU housing to cool the internal transformers and capacitors, and exhausts the warm air out through the mesh grid at the back.
Option A: Fan Facing Down (Recommended for most cases)
Most modern cases feature bottom-mounted PSU slots with a mesh filter.
- Pros: The PSU acts as an isolated cooling loop, pulling cool air from under the case and exhausting it directly out the back without heating the internal PC chamber.
- Cons: If placed on carpet, airflow is blocked, causing the PSU to overheat.
Option B: Fan Facing Up
Mount the PSU with the fan facing up if:
- Your case is resting on thick carpet that would block bottom vents.
- The case has a solid metal bottom panel with no vents.
- The PSU shroud features ventilation holes, allowing the PSU to act as an auxiliary exhaust fan for the GPU chamber.