To me, an ATX power supply is one of those big boxes delivering 500W+ inside a PC tower, but since it’s not possible to create hardware with much lower power consumption, HDPLEX has designed an ultra-compact 250W passive ATX power supply using the same GaN (Gallium Nitride) technology as found in some tiny USB-C power supplies.
With a 170x50x25mm footprint, the company claims it is the world’s smallest ATX PSU, and it is especially well suited to SFF PC enclosures, but it should also work pretty well in other space-constraints applications with a board equipped with an ATX connector, or through an adapter board, or even some RGB LED projects.
GaN ATX power supply specifications:
- Wattage – 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 – <0.4W/0.1W
- Noise level – zero dB operation with fully passive/fanless design,
- PFC+LLC Structure, Level 5 energy efficiency
- 2x auto grade GaN FETs on PFC stage and 2x on LLC stage
- 1.18W/cm³ power density
- Three Stage AC input filter to eliminate grid noise
- 4x ATX 1KV 8A TTR8MF Full-wave rectification
- 150µF Rubycon filter CAP and 9000µF Solid Cap
- Protections – UVP, OVP, SCP, OPP, OTP (See Coolmaster article for an explanation of those terms)
- Detachable C14 IEC connector to support other AC input for custom projects
- Dimensions – 170 x 50 x 25 mm, (Aluminum shell casing to help dissipate heat)
- Temperature Range – -10°C – 75°C
If 250W is a bit tight on the power budget, it’s possible to connect (aka sync) two units for a combined 500W of output power. The PSU ships with several cables:
- 20 cm IEC C14 AC- two ELR connectors cable
- 25 cm 24-pin (20+4) ATX PSU cable
- 45cm CPU EPS 8-pin (4+4) cable
- 45cm PCIe with red connector with dual 8-pin (6+2) cable
- 45cm SATA power cable with 4x SATA power connector
- 45cm sync cable (45cm)
The HDPLEX 250W GaN All-In-One ATX PSU will be available in June for $145 with free worldwide shipping from warehouses in the US and Germany.
Via FanlessTech

Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.
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