Computer submersed in water?

EDIT: Oh, and the idea that the computer would cause the release and subsequent ignition of hydrogen gas is just absurd.

Why is that? The positively charged hydrogen ions will naturally move toward the negative power supply and assuming there is exposed leads, they will gain electrons, form H2 and bubble into the air. If the actual PSU is in the air and in close proximity, it could be a source of ignition.