Other World Computing DT01ACA 3.5" 7200rpm 64MB SATA 6Gb/s (HDKPC09) - 2.0TB

OWC's in-line solution is the only hardware digital thermal sensor on the market allowing a third-party SATA drive to be installed in your iMac. A convenient, plug-and-play cable, the In-line Digital Thermal Sensor eliminates fan noise and maintains proper system fan control through the iMac's System Management Controller. This innovative device is designed specifically for the iMac, requires no software hacks and ensures compatibility with Apple's built-in diagnostic processes.