As I planned to use yume not only at home but also in a car I had to build a power supply that can handle both 230V and 12V input voltages.
The core consists of several DC-DC regulators which allow the input voltage to range from 10V to 15V. This is especially important when powering yume in a car where the voltage can (during ignition) be lower than 12V.
The switch-mode regulators are powered directly when used in the car and by a transformer/rectifier combination when using 230V.
The rest of the power supply is responsible for providing the 5VSB (5V standby) voltage and switching the main power supply if the PC is turned on (ATX-support):

size of image in full size: 511k

Well... I had to do some compromises during development because I had some parts lying around and wanted to use them. If you want to build this PSU you may want to replace some parts. The ones that you could/should change are listed below:

part in schematics
may be replaced by
transformer 6V, 2VA (=333mA) transformer 6V, 0.6VA (=100mA) my LCD backlight draws ~100mA so I need some more current than you may do
the two 1N4001 diodes on the right two schottky diodes 0.1A/10V (BAT43, BAT45, SB130...) schottky diodes have a lower voltage drop
the two 10k-resistors two 100k-resistors you may blow the PSUON circuit on the mainboard if the transistors draw to much current from it! If 100k is too much (the relays don't switch) you can still take the 10k resistors
transformer 15V, 80VA any transformer with 10 to 15V and >70VA
0.315A fuse 0.5A fuse if you have a more powerful main transformer
the two P600K diodes any schottky diode with >20V and >8A (MBR1645, SB1020 and such) lower voltage drop than normal SI-diodes, important if voltage in the car is lower than 10.5V

Note: the upper relay has to be able to switch at least 0.5A at 250V and the lower one has to be able to switch at least 8A at 12V. To be prepared for the future (second HDD) I assume that yume consumes 80W, although it will only consume 65W.