Fanless & Passive Power Supplies
Building a completely silent computer requires fanless components. This guide outlines passive thermal management and sizing for fanless PSUs.
Thermal Design of Passive PSUs
Fanless PSUs do not have a cooling fan. They use heavy internal heatsinks, highly efficient components (usually 80 PLUS Platinum or Titanium), and a perforated chassis to dissipate heat.
Because they rely on natural air convection (warm air rising), they must be installed with their ventilation grids facing upward, allowing heat to escape easily.
Case Airflow Requirements
While the PSU has no fan, the chassis must have adequate ventilation. Placing a fanless PSU in a sealed case without system intake fans will cause it to overheat and trip its Over-Temperature Protection (OTP).
⚠ Wattage Limit: Fully passive ATX power supplies are typically limited to 500W to 700W. If your gaming configuration demands more power (e.g. RTX 5080), choose a semi-passive (semi-fanless) unit with a Zero-RPM fan mode instead. The fan will remain off under 40% load.