Pico PSU

As part of my ongoing Mini-ITX hobby project, I decided that it needs to be quieter because it lives in Lucy’s bedroom and is powered-on 24×7. With today’s energy prices, I also wanted to make sure it was as low-power as possible.

The existing PSU was the one supplied with the case: an already low-power (110W) job with a single quiet fan. The motherboard itself is a fanless-design Epia SP from VIA. There were also two small (40mm) fans in the case to keep some airflow moving because of the standard-size DVD writer and a belt ‘n braces 80mm fan to keep things nice and cool elsewhere. The fans were software controlled based on CPU temperature, but they still ran about 20% of the time keeping things cool.

I decided to have a re-think and get rid of the DVD writer – I can always create the ISO images on the Linux machine and then transfer them to my main PC for writing at a later date. That’s a huge power drain gone (upto 31.5W peak). Taking the fans out dropped power consumption by another 2W.

I also decided to ditch the original power supply and bought a picoPSU. This is a nifty little device which is tiny and plugs directly into the motherboard ATX header. As you can see from the picture below, there’s very little to it and crucially, no fans in sight. The main thing to note is that it’s tiny. Two 50p pieces would easily cover it. The whole unit is powered by a “brick” which is a bit like a laptop power adaptor: again a fanless component.


It arrived the other day and later that night I took the system apart and after some fiddling, installed it into the case. The DVD writer was removed, along with the power supply, the three redundant fans. Even for such a small case, there was a lot of room. The other surprising this was that I found the whole PC was so much lighter than I had been expecting.

Anyway: time for the big test. I plugged everything in (minus a monitor: it never uses one anyway), pressed the power switch and some lights came on, but nothing seemed to happen. Bugger: I must have got a faulty one. And then the system beeped it’s usual happy POST complete beep. Eh?

Ah yes: I’m so used to building regular PCs I was used to various fans spinning up and hard drives whirring into action. The whole mini PC boots Linux off a 256MB compact flash card, with main storage on an external USB hard drive. So with a fanless motherboard, fanless PSU, and no hard drive, the thing is totally silent. It’s a little unnerving at first to build a PC which is completely silent, but I was suddenly very happy with how quiet things were.

It’s been running continuously for over 2 days now and the internal CPU temperature is quite happy hovering around the 52C mark – up slightly from 43C previously. That might sound high, but it’s well within the standard operating temperature guidelines. Overall, power consumption dropped from 32W to 21W. In real money, that equates to a saving of about a tenner a year in electricity.