In a post today on its Rocket Yard blog, Other World Computing (OWC) announced a new in-line digital thermal sensor for owners who want to upgrade the hard drives in their iMacs. The sensor kits are compatible with models from 2009 all the way up to the latest 2014 Retina 5K model, allowing the use of third-party replacement hard drives (which the company conveniently sells), overcoming a troublesome proprietary issue on the machines.