For me, an ATX power supply is one of those big boxes delivering 500W+ inside a PC tower, but since it’s not possible to build hardware with much lower power consumption, HDPLEX has designed an ultra-compact 250W passive ATX power supply using the same GaN (Gallium Nitride) found in some tiny USB-C power supplies.
With a footprint of 170 x 50 x 25mm, the company claims it’s the world’s smallest ATX power supply, and is particularly well-suited to SFF PC cases, but it should also perform quite well. well in other space-constrained applications with a board equipped with an ATX connector, or via an adapter board, or even some RGB LED projects.
GaN ATX power supply specifications:
- Power – 250W (94% efficiency).
- Input voltage – 90V-264V 50/60hz
- DC output
- +3.3V up to 10A
- +5V up to 10A
- +12V up to 20A
- -12V up to 1A
- +5VSb up to 3A
- Max combined power for +3.3V and +5V – 80 W
- Total power – 250W
- Idle Power –
- Noise level – zero dB operation with fully passive/fanless design,
- PFC+LLC structure, energy efficiency level 5
- 2x auto-grade GaN FETs on the PFC stage and 2x on the LLC stage
- Power density of 1.18 W/cm³
- Three-stage AC input filter to eliminate mains noise
- 4x ATX 1KV 8A TTR8MF Full wave rectification
- 150 µF Rubycon filter CAP and 9000 µF solid cap
- Protections – UVP, OVP, SCP, OPP, OTP (See the Coolmaster article for an explanation of these terms)
- Detachable IEC C14 connector to support other AC inputs for custom projects
- Dimensions – 170 x 50 x 25mm, (aluminum housing to help dissipate heat)
- Temperature range – -10°C – 75°C
If 250W is a little tight on the power budget, it is possible to connect (aka sync) two units for a combined 500W power output. The PSU comes with several cables:
- 20cm IEC C14 AC cable – two ELR connectors
- 25cm 24 pin (20+4) ATX power cable
- 45cm CPU EPS 8 Pin (4+4) Cable
- PCIe 45cm with red connector with dual 8 pin (6+2) cable
- 45cm SATA power cable with 4 SATA power connectors
- 45cm sync cable (45cm)
The HDPLEX 250W GaN All-in-One ATX Power Supply will be available in June for $145 with free shipping worldwide from warehouses in the US and Germany.
ViaFanlessTech

Jean-Luc started CNX Software in 2010 on a part-time basis, before stepping down as Director of Software Engineering and starting writing daily news and reviews full-time later in 2011.