Apple has taken an interesting position in its upcoming iMacs that support Thunderbolt. Other World Computing, a third party hardware vendor for Apple products, has announced that the main hard drive cannot be changed, or even moved. The company did find that a second drive could be installed without issue. The problems with the main drive arise because Apple decided to swap out an industry standard connector for a proprietary connector. Also installed was a proprietary temperature and fan control system. Without these two components, the system will fail an Apple Hardware Test and won't function. The only drives that can be used as a main drive will be those available through Apple.