SFXPSUs

SFX power supply units, or SFX PSUs, are power supplies designed in the SFX form factor for compact computer cases and small form-factor builds. The standard SFX footprint measures about 125 mm wide by 63.5 mm high and around 100 mm deep, smaller than a typical ATX PSU. A longer variant, called SFX-L, increases depth to roughly 130 mm, enabling improved cooling and higher wattage.

SFX PSUs cover a range of wattages, commonly from 350–750 W, with higher-wattage models available from select manufacturers. They are designed to deliver stable 12 V rails while maintaining efficiency, often achieving 80 Plus Bronze to Gold or higher certification. Cooling is achieved with a small fan, typically 80 mm or 92 mm, and many units implement adaptive or silent fan profiles to balance noise and temperature. Some SFX-L units use a larger fan and airflow optimized for lower temperatures.

Most SFX PSUs are modular or semi-modular, with cables tailored for compact builds. Typical connectors include a 24-pin ATX, one or two 8-pin (EPS) CPU connectors, and PCIe 6+2 pins for GPUs. Drive connections are provided via SATA and sometimes Molex. Cable lengths are generally shorter than those on standard ATX units, so case compatibility is an important consideration.

Applications: SFX PSUs are common in mini-ITX and compact cube cases, HTPCs, and other space-constrained systems, where a regular ATX PSU would not fit. They are valued for keeping a clean build and allowing flexible GPU mounting in small form-factor cases; however, they can be more expensive per watt and have limited space for extra rails or top-end GPUs.

Limitations and considerations: Case compatibility is crucial, as SFX units require a case designed for them. Some cases that support SFX do not allow long GPUs or certain cable routing. Thermal performance can be stronger with SFX-L models, which also tend to be heavier and more expensive. All SFX PSUs include standard protections such as over-voltage, under-voltage, over-current, short-circuit, and over-temperature safeguards.