Chosen Solution
Hi, I am wanting to replace my 1TB Hdd in my 27" 2012 iMac. I have purchased the Samsung 840 Pro 256gb SSD but I read somewhere that you will need third party software to control the fan speeds once you remove the original HDD. Is this true? I thought the 2012 iMac didn’t require the temperature sensor on HDD because of it being built into HDD. Do SSD’s need a temperature sensor? Do they have them built in? Many thanks, Will
Sadly SSD’s don’t offer an internal temp sensor that meets Apples spec. Here’s a good writeup on what Apple did OWC - iMac HD Upgrading explained. The correct way to deal with this issue (if your HD don’t come with the needed sensor) or replacing the HD for a SSD is to get this kit: OWC Complete Hard Drive Upgrade Kit Including Tools for all 27" iMacs 2012 & Later. A better solution is to leave the HD in and install the PCIe M.2 blade SSD the system is able to support (some are just now being made available by 3rd parties) or get a SSHD hybrid drive (Seagate) that has the needed internal sensor so you don’t need to adapter kit.
HDD Fan control application is 38$ and solves the problem.
Upgraded my late 2012 27” iMac (13,2) with a Samsung SSD, but was not sure about buying the OWC sensor, so before re-sealing the screen, I booted up and it appears the SSD temperature is monitored without the need for the OWC external sensor. Temperature of SSD is about 21 Celsius and fan is on low speed. See screen shots below.
Update (10/13/2019) In case the above image is too small.
Can someone clarify this answer. I just ordered the kit, and need instructions on installing the sensor maybe… there is an SSD in there now, albeit now beat, that was reporting temp for years…
