I am working on an iMac which seems, from the best I can tell, to have a failing SSD from a fusion drive. I've removed the HDD and replaced with an SSD, but the system still crashes spontaneously, seemingly related to the AppleSSD becoming "noticed" by the OS. Generally the OS doesn't even find that SSD, and when it does, and I go to format it, it does not ever succeed. So if I could disable the SSD, that would allow me to tell if the crashes are caused by the SSD. I've already tried replacing the RAM and of course I've already replaced the HDD with an SSD. Taking the computer apart to remove the SSD physically is more work than it's worth costwise, but if I could disable the port somehow like you might be able to do via a PC bios, that would be a quick way to test my theory. Any idea on how that would be possible? I have already told it not to mount in disk utility, but that doesn't do the trick because it seems to disappear and reappear on its own. It's a 2013 iMac.