[G4] External Drives Not Mounting

[Ronald Steinke]

I, also, had a problem with an external drive not mounting but the  
problem was with my new G5 tower, not a G4. The drive shows up  
immediately upon powering it up when it is attached to the G4, but  
will not appear at all with the G5. The G5 is a late 2005 2GHz Dual  
Processor model with OS 10.4.8, 1.5Gb RAM, 160 SATA drive.

I tried System Profiler, Disk Utility, DiskWarrior, and TechTool Pro  
with the G5 and had no indication that the external drive even  
existed. As soon as I moved it to the G4, it showed up. The G4 will  
see it every time, but not the G5.

I have no idea why and everything I have tried gives no success:  
switching cables, trying the USB instead of FireWire connection on  
the case, third party utilities, etc.

I finally tried putting the extra drive into a different case.  
SUCCESS at last, but I still don't know why it is working with one  
machine and not the other. Can a difference between external cases  
make this happen?