IIRC, guys@empeg use IBM and Toshiba, but good results are reported with Fujitsu and others. The drive should not be thicker than 12.5mm (1/2") (actually, 17mm is mentioned in some places, but let's be on the safe side and give the drive more room to wiggle while we drive on potholed roads). If it draws too much current at startup, gets too hot or takes too long to spin up, the empeg might have problems with it; however, we have not heard here that any drive from major manufacturers displayed any of these problems.
When upgrading, take care not to ignore advice from the FAQ on insulating the bottom of the drive from the carrier plate and installing enough washers on the mounting screws as to ensure that the spindle is relieved of any pressure (taking care, of course, of staying within allowable hight).
Dragi "Bonzi" Raos
Zagreb, Croatia
Q#5196, MkII#80000376, 18GB green
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Dragi "Bonzi" Raos
Q#5196
MkII #080000376, 18GB green
MkIIa #040103247, 60GB blue