Other World Computing (http://www.macsales.com) has announced an expansion of the In-Line Digital Thermal Sensor HDD DIY Kits (http://tinyurl.com/ogeb2q9), with support for 2009 and newer iMac models, including the latest iMac Retina 5K display.
OWC’s in-line solution includes a custom hardware digital thermal sensor allowing a third-party 3.5-inch SATA hard drive to be properly installed in an iMac, enabling full compatibility with Apple Diagnostics and the iMac System Management Controller. A plug-and-play cable, the In-line Digital Thermal Sensor eliminates excessive fan noise and maintains proper system fan operation while requiring no software hacks.
Using an OWC Internal HDD DIY Kit, you can replace the original iMac hard drive with up to a 6TB hard drive (sold separately). The kit is available for immediate ordering at special “OWC Holiday Saver” pricing starting at US$57.