Hello all, First I want to thanks everybody that support me on this problem. I do not thank Formac for there lousy support. This mail is to inform you that now my SCSI chain is working very well. Manfred Maraum from Emagic DE found THE SOLUTION to my problem, it was very tricky, gues what ? the cable between my Yamaha 4416 and my Akai S2000 sampler was not liked by the FORMAC card. On the cable that had problems I have a grey thing (looks like a condenser) I have changed the cable to a normal SCSI cable and it is working like in a dream, I can switch On and Off my SCSI devices while I am working on the G4/400. Resumé of the problem to be added in Tips and tricks : My SCSI Chain : G4/400 ==> Quantum 540MB Akai formated ==> YAMAHA CRW 4416 ==> AKAI S2000 SAMPLER The Sympthoms where : Your G4 would not start if the Akai formated HD is not powered up Your G4 will freeze if the Akai formatedd HD is powered down If I forget to turn on and to load my Akai Sampler I get SCSI ERRORS (unrelyable connection) when I burn a CD The same SCSI chain was working very well with my PowerBook Wall street G3. Cyril Blanc