I can see that it is not that difficult to replace HDD in my imac. Only question I have is this, do I need a temperature sensor cable with a 2.5" SSd drive? Some youtube videos say yes others say no. Your help is greatle appreciated.
I switched out the hard drive on a 27" 2011 today and I can confirm that the hard drive sensor that attached to the drive is gone. I put in a Seagate 1 TB SSHD and it's running just fine. No modifications were needed. - iMac Intel 21.5" EMC 2428