A PCI audio add-on card seems to be working correctly, except that there is no sound at all.
Does this something have to do with this power supply?
Yes, it might. Some PCI sound cards do use the negative 12V rail of the ATX specification.
This rail is not required for the Mini-ITX standard and therefore omitted.
Can the power supply be operated in a closed and unvented case?
No, not really. For maximum performance the power supply must be cooled by a decent airflow
from the system fan. This is especially true in higher ambient temperatures and when using
1GHz Epia boards.
If you encounter sudden shutdown of the system, first check the airflow at the PSU.
Be careful when touching the power supply and especially it's heatsink!
This heatsink can reach temperatures beyond 100°C!
Why won't the system start with this power supply and XYZ harddrive?
Certain harddrives are very strict voltage requirements. During the spin-up phase however,
the regulated 12V from the power supply can drop below the harddrive threshold level. This
causes startup problems.
Western Digital Caviar series harddrives have been verified to work correctly with this