Source : Apple DiscussionsMost review sites have already lamented about the insufficient USB ports (currently 5) on the top-of-the-line pro systems. Certainly one were not expecting underpowered ports too. Well, apparently it happens only when one uses all the 5 ports and especially true when the ports are connected to another hub (e.g. a Dell display with a built-in USB hub etc). These hubs appears to draw an excessive amount of power which unfortunately interferes with the other ports. Interestingly, these built-in hubs (within displays) should not require additional power as they are independently powered.
The above paragraph is certainly nothing conclusive, but whatever the actual reasons may be, you know what to look out for when you are unable to mount a thumbdrive, even when
