Sure, I have an old PC with an energy efficient mainboard and a PicoPSU and I wouldn't want anything else. I believe it does somewhere around 20W-25W though. And I have lots of RAM, a decent (old) CPU and enough SATA ports.... Well, I would go for a newer PC, they get more energy efficient all the time... But it's a lot of effort to pick the components unless some PC magazine writes something or someone has a blog with recommendations.