I cant seem to get my external 3.0 usb hub to work with my 2012 imac. Ive tried all the ports and they all work without the hub. The hub is powered but that doesnt seem to help. The hub lights up like it knows something is connected but it never shows up in osx. this is the hub im using. http://www.amazon.com/Oct-2012-Upgr...ie=UTF8&qid=1364323166&sr=8-1&keywords=uspeed I have tried it on my other mac and the hub works perfectly. it just doesnt work with the 2012 imac. Ive tried rebooting, various resets, various ports. repair permissions. im out of ideas.