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HDPLex’s ATX PSU Is Barely Bigger Than a Phone

HDPlex's really small ATX PSU
(Image credit: HD Plex)

Apart from monitors (opens in new tab), everything in computing tends to get smaller over time. While power supplies have remained the same size for many years, Fanless Tech has discovered this passively cooled ATX PSU from HDPlex (opens in new tab) that’s only slightly larger than an iPhone, and claims to be the world's smallest at 170 (D) x 50 (W) x 25 (H) mm. 

HDPlex's really small ATX PSU

(Image credit: HD Plex)

The model in question only provides 250W, so probably isn’t one to get for a gaming rig (though you can combine two using a sync cable to make a 500W unit, one for the motherboard and the other for the GPU), but the sheer size of them makes them perfect for custom small-form-factor builds.

The PSUs are fanless and should be  completely silent in use. They offer 94% efficiency and use a unibody flat transformer to eliminate noise from vibration, making it ideal for home theater PCs. The copper PCB and aluminum casing are tuned for heat dissipation, and if you get one of HDPlex’s fanless chassis, it will act as a heat sink.

The trick to the compact nature of the PSU is the use of auto-grade Gallium Nitride in the FETs for the PFC and LLC stages, allowing a high power density of 1.18W per cubic centimeter. 

Gallium Nitride is a binary III/V semiconductor used as an alternative to silicon. It helps improve power density by allowing much higher sustained switching frequencies, which mean smaller working parts, and can keep working under higher temperatures. An equivalent field effect transistor made from silicon would require cooling, taking power away from the device it was trying to drive. The cost of production for GaN devices is also lower, as they are smaller and don’t require cooling fans to be built in. It’s the technology behind the ever-smaller and more powerful USB chargers that are proliferating on online stores, and other compounds of gallium, such as gallium arsenide, demonstrate significant improvements in electron mobility (opens in new tab) when used to create transistors.

The PSU will be available from June this year, and is priced at $145 with free shipping worldwide. The package contains the PSU, sync cable, and five modular power cables.

Ian Evenden
Ian Evenden

Ian Evenden is a UK-based news writer for Tom’s Hardware US. He’ll write about anything, but stories about Raspberry Pi and DIY robots seem to find their way to him.

  • tennis2
    I could use one of these for a custom build!!

    Also: (flexATX)
    https://www.silverstonetek.com/product.php?pid=935&area=en
    Reply
  • wr3zzz
    What is the use case for a 250W ATX PSU? With such power cap you are better off using a laptop. Better form factor plus mobility.
    Reply
  • BillyBuerger
    These look really nice. One of these will easily power a 65W CPU plus a 90W GPU which is what I have right now. At some point I'd like to upgrade to a better GPU but still would like to stay below 150W. Probably an RX6600. Could possibly handle it with one of these. But they're small enough that it looks like I could fit a second in my case should I feel I'm pushing the power too much. I was looking at flex ATX but I think these would work even better.
    Reply
  • mikeebb
    Adding a PSU for a new (to me) GPU is a prime use case. While the PSU I have is probably good enough for the GPU I'm looking at, it could get marginal if everything in the system gets pushed to the max at the same time. Should that happen, I could separately power the GPU with one of these. Interesting. Of course, a new conventional PSU might also not be much (if any) more expensive.

    The article mentioned what I suspect is the real target for this thing: HTPC (if anybody builds those any more). Another possibility might be a small NAS that's not kept in a closet.
    Reply
  • hotaru.hino
    wr3zzz said:
    What is the use case for a 250W ATX PSU? With such power cap you are better off using a laptop. Better form factor plus mobility.
    A low power setup like a NAS box, media server, or just any other basic PC. Assuming this has some quality behind it, it also brings a breath of fresh air in this market because most of the sub 400W power supplies are garbage.
    Reply