I'm in the US and to get my G7400 running I bypassed the whole internal PSU. If I remember correctly, the boards in a G7400 require 5V and 12V (the G7000 might only require 5V, not sure).
I had a broken external CR-ROM player whose external PSU gave 5V and 12V (I think all hardrives/cds need 5v/12v), so I ripped out the jack of the CD and wired it to the G7400. It's an ugly hack and fragile hack, but it works. I really should mount it somehow.