I've trawled through Google search results to see if I could find an answer to this question, but everything has been inconclusive so far. I thought I'd ask here to see if anyone had any real experience with it. Basically, I have a rMBP on order and the SSD is only 256GB. As I will be limited on space, I'd like to keep all non-essential items on an external HDD (including games). I have already purchased a USB 3.0 5400rpm WD My Passport just to get the files off my old MBP for selling. My intention is to pick up a WD MyBook (2TB, USB 3.0), which will have its own power supply. While I'm certain the WD MyPassport is a 5400rpm drive, I'm not certain about the MyBook (it could be 7200rpm, but I have my doubts). Here are my questions: 1) Is it possible to play games (of the caliber of say, Mass Effect 2, Skyrim, etc) on an external HDD over USB 3.0 AT ALL? I had problems with running games off of USB 2.0 - Steam games like Left4Dead 2 were choppy and eventually froze. 2) Other than loading times, will the 5400rpm drive make games unplayable even if connected over USB 3.0? I used to play games over a 'green' 5400rpm SATA drive in my PC with no problems at all, but I wonder if USB 3.0 will cause me an issue. 3) Do I need a hard drive with its own independent power supply to play games over USB 3.0, or will something like the MyPassport also work? Basically, does playing games zap more power from the USB connection? If so, would an independently powered USB 3.0 HDD like the WD MyBook or any internal 3.5" drive in an external enclosure solve this problem? Would I be able to play games 'on-the-go' with the WD MyPassport, or will I be limited to playing them only when connected to a 'desktop-sized' 3.5" external HDD? Thanks!