Hi All, I've spent the past hour trawling through the net and macrumors looking for a solution to a problem I have. I originally had a 1TB seagate on my Mid 2010 iMac. With applecare expiring last month, I very boldly decided to perform some surgery and add a 500gb SSD, while upgrading the HDD to a 4TB WD Caviar Black. I've managed to successfully install Snow Leopard from the iMac discs onto the SSD, upgraded to Mavericks. However, all this time, I have been unable to format my 4TB hdd. The symptoms are: - Listed in Disk Utility, but does not have a drive name - All options/buttons for First Aid/Erase/Partition/RAID/Restore are greyed out and cannot be clicked. - Disk details as below: Disk Description : WDC WD4001FAEX-00MJRA0 Media Total Capacity : 0 Bytes Connection Bus : SATA Write Status : Read/Write Connection Type : Internal S.M.A.R.T. Status : Not Supported Partition Map Scheme : Unformatted Everytime I start up the iMac, I get a pop up alert "The disk you inserted was not readable by this computer." with an option to Initialize (brings up Disk Utility as above), Ignore, or Eject. I am wondering whether there is something I've missed, or if my HDD is dead, or if there is a compatibility issue between the HDD and the iMac. Help me macrumors forum, you're my only hope!