Hi guys, A few years ago i added an SSD drive to the optical bay of my 27" 2009 imac and made a do it yourself fusion drive. Over the past few weeks however, the original mechanical drive (still in its original bay) has started failing. As it is such an old computer I didn't want to spend anything on it, so I just broke the core logical volume back to the original two stand alone drives and installed OSX on the SSD (which is in the optical bay). I then found a command to stop OSX mounting the mechanical drive at all. So although it is still in the machine and plugged in, it never appears or does anything in OSX. All was well until today, when the failing drive seems to have failed further and now has it's fan (HDD fan) spinning at around 4,000 rpm which is very loud, I tried using SMC fan control to slow it down but it just ignores it. I guess the mac is panicking that the HDD is failing/getting too hot and so is running the fans quickly? My question is, is it possible for me to just open the iMac, disconnect the mechanical HDD's power and then run the mac as normal, or will it not like the fact there is no drive registered in the original HDD bay and only has an SSD in the optical drive bay which it thinks should be a CD drive? Many thanks EDIT: Is it ok to leave a failing drive in the iMac like that? I thought as it was failing and not mounted, it would just pack up and stop working and that would be that. I didn't expect it to go haywire and start telling OSX to run its fans at crazy speeds.