via some Dutch Dude who didn’t have any issues installing an SSD in the Hard drive Bay
According to a blog post at OWC, the new iMacs have a temperature sensor in their hard drives which will restrict replacing with non- hard drives.
For the main 3.5″ SATA hard drive bay in the new 2011 machines,has altered the SATA power connector itself from a standard 4-pin power configuration to a 7-pin 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).
Here’s the thing though: What if you order an iMac without a hard drive? One iMac option is just the SSD which is mounted on the optical drive? Perhaps there is a way to disable fans altogether and thats what ships with SSD-only iMacs?
Clearly some more investigative work is necessary.