Apple Further Restricts Upgrade Options on New iMacs

Since Late 2009, there's been a well-documented issue with the iMac line. If you upgrade the hard drive, the fans can start spinning like crazy.

For the main 3.5" SATA hard drive bay in the new 2011 machines, Apple has altered the SATA power connector itself from a standard 4-wire power configuration to a 7-wire configuration. Hard drive temperature control is regulated by a combination of this cable and Apple proprietary firmware on the hard drive itself. From our testing, we've found that removing this drive from the system, or even from that bay itself, causes the machine's hard drive fans to spin at maximum speed and replacing the drive with any non-Apple original drive will result in the iMac failing the Apple Hardware Test (AHT).