About Power Supply Units

Mike Chin, at SilentPCReview has some great information about Power Supply Units (PSUs).

He has a section on Power Supply Fundamentals, a list of Recommended PSUs, and -specially interesting to us- a review of the Sparkle Power SPI220LE 80 Plus FlexATX, specialy well adapted for low-consumption, as it can maintain over 70% efficiency at 20W. usage.

Finding good power supplies for our project is not specially system.

We need power supplies that have a low wattage (under 100W if possible). Power supplies only use the power that is being demanded by the system, but power supplies that are prepared to deliver a lot of power do not perform specially well when the demand is very low, reducing their efficiency.
The power supply's fan permits circulation of air throughout the system. Without this, we would have to put our own fan in the chassis. Fanless power supplies are not necessarily an advantage.
In the boxes that we are planning, the power supply will touch the chassis both above and below. The power supply must have its outside grid (together with the plug for electricity) in one side, and the fan in the opposite side. Having the fan inside, and nt outside, next to the plug, reduces the noise.
If possible, the power supply should not be higher than 6 cm., nor longer than 15cm.
Must have standard ATX cables.

There is an in depth article on computer power supplies here on wikipedia
Some Power supplies

Some which could be interesting: