Interesting that you should ask. I was wondering whether spin-up current could be a factor with the dreaded "No HD found" message, and whether the Fujitsu drives draw more current during spin up than others, as most people see more problems with the Fuj drives. (The specs I found didn't support this theory, but we all know that specs get massaged).

I was also wondering if it might be ground related - the rubber mounting washers mean that all spin-up current has to return through the IDE cable. For 2 Fujitsu drives, that is 1.8A (assuming they spin up togther). I don't know what the resistance of the IDE cable is - but the drives are only spec'd for 5V +/-5%. And some people suggest that switching Master/Slave on the cable helps. I wonder if they spin up in order, and the difference in cable length is having an effect.
Lots of random musing, but no concrete theories.