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X7-ATX-500 - 500W PicoPSU for custom and small form factor builds

X7-ATX-500 is a DC-DC passive ATX power supply that can be used in small form factor and fanless builds. Due to it very small dimensions it allows for taller CPU coolers in cube cases where normal ATX power supply would limit it.

In this article I'll go over the X7 power supply and it capabilities.

X7-ATX-500 power supply

X7-ATX-500 power supply

TK40P04M1 voltage regulators

TK40P04M1 voltage regulators

X7-ATX-500

The power supply can be bought on Aliexpress, ebay and some local Pico-PSU/small form factor oriented shops for around $110 or more. Additionaly you will need one or two power bricks with 7.4mm x 5.0mm plug, like HP 230W HSTNN-LA12. Refurbished they cost around $10-15 but it can depend on region. The PSU is compatible with ATX mounting holes and has two power brick plug connectors on the back.

X7-ATX-500 is a DC-DC power supply that is completely passive and is only ~3 cm tall (versus 14 cm in an average ATX power supply). It can be used in fanless builds or in small form factor builds where a full sized ATX power supply would be problematic to use. In cube cases where the ATX PSU would be mounted above the motherboard this PSU would allow for using taller CPU coolers as there would be no PSU housing limiting the clearance. Just note that a taller and larger radiator with a bigger fan would also blow air on the PSU which is handy, although if the CPU is for some reason constantly really hot this could impair PSU performance/trigger overheating safety features. Running 9900K is thus not recommended ;)

To power the mainboard you will need one power supply brick. To power GPU PCIe connectors you need the other brick. First brick will provide power to the CPU, storage, RAM, the motherboard as well as things connected to the PCIe slots. The limit is 75W for a x16 slot but some GPUs were known to draw bit more. If a GPU has additional connectors it gets the separate 12V rail via the second power brick.

HP 230W HSTNN-LA12
HP 230W HSTNN-LA12 power plug

HP 230W HSTNN-LA12 power brick

Based on power bricks used you may want to limit how much power the system uses. If you have a 230W PSU then you should aim at like 180-190W max draw if not less. For GPU the safe max would be a 8-pin + 6-pin type of GPU. Those going all in with two 8-pin and consuming close to 300W aren't the best choice for this setup. The total power this PSU is rated for is 500W.

Usage cases

I used X7-ATX-500 with Jonsbo C2 small mATX case, which you can check out here:

Ryzen 2200G APU build worked just fine, and to push it I also added a mini GTX 1070 and powered it via second power brick. In such small and airflow limited case the temps did not exceed 80C (GPU hottest) during CPU/GPU stress testing. I also used a tower CPU cooler instead of a low profile one mandated when using a normal ATX power supply.

Airflow is limited but the CPU cooler should help directing hot air to the exhaust

Airflow is limited but the CPU cooler should help directing hot air to the exhaust

GTX 1070 just after opening the case during stress test

GTX 1070 just after opening the case during stress test

There are fanless GPUs like KalmX 1050 Ti and 1650 as well as fanless CPU coolers which for low loads / low power parts would work fine. For more demanding tasks you will likely need some airflow to keep the components from overheating. KalmX can get really hot under full load but also drastically drops temps when given even some airflow. To make it as noiseless as possible I would recommend a case with a large intake fan that doesn't have to spin fast to push enough air. There are cases that use common 200 x 200 mm fans but there are more custom ones with much bigger intake fan. Good quality fan on a big enough CPU cooler radiator should also be nearly noiseless as well.

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Hardware benchmarks and reviews, 17 May 2020, Piotr Maliński

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