Last hard drive went out on my 2007 imac 21.5". Was recommended to get a WD Caviar Black so picked up this drive: http://eshop.macsales.com/item/Western Digital/WD1002FAEX/ Installed it last night but noticed that it had no option to plug in the temperature sensor. This wire: http://www.impactcomputers.com/593-0998.html Here is a side by side of the old drive and the new one: http://i.imgur.com/cxA4cyA.jpg Read around and heard that not having this plugged in will just keep the fan running so put the imac back together to format and install OS X 16.1. When re-installing OS the screen just remains gray through as soon as it turns on. Still gets the mac "chime" but it will wait a moment, make some noise and then spit out the install disk. Tried pressing "C" on the keyboard, but the only keyboard we had was bluetooth and the green light would not stay on. It would just flash on and off. Replaced batteries in keyboard, restarted and even tried pressing "Command + R" but got nothing but a grey screen. Tood disk out and turned on normally and still only got gray screen, not even screen with folder with a question mark. Do we need a usb keyboard to do the first install of a new hard drive? If so, does it have to be a mac keyboard? Is there a problem with the hard drive purchased? Thanks!