I recently purchased an 27" Retina iMac, 4Ghz i7, 16GB ram. I plugged in two external drives - a Seagate and a WD through a Dynex USB 2 Port Hub. Both worked fine. I imported pictures from both drives using Lightroom 5.6. Then I plugged in a different Seagate drive - FreeAgent GoFlex (also through the Dynex hub) - and got the message "USB Devices Disabled - Unplug the device using too much power to re-enable USB devices". I've been using this Seagate GoFlex drive on my MacBook Pro for nearly two years without a problem. I then plugged the GoFlex drive back into the MacBook Pro and got the same message (which I've never had come up before on the MacBook). Lastly, I replugged the GoFlex back into the Dynex Hub and the Hub back into the iMac. The Dynex hub started to smoke. I disconnected both the drive and the hub. Needless to say the hub is toast, but I'm wondering if there is any way to re-access the GoFlex drive either on the iMac or the MacBook.