Not 100% sure on that. When I install internally in the SE/30 with termination on and SCSI ID 0, it doesn't freeze, but HD SC Setup (patched version) fails to recognize it. When I install it in the external case and use it with the IIsi, it freezes the computer on boot unless I boot with it off, then freezes the computer when I turn it on. I haven't tried it internally in the IIsi or externally with the SE/30, though I suppose that might be worth a shot...