Hi All, Im considering to buy a new iMac base model ( 8GB RAM, 1TB 5400RPM HDD) and want to explore an option of booting this one form the external USB3 port with SSD. Considering USB3 speeds are similar to SATA3 I think I would be able to achieve the same level of speeds as if I have internal SSD. The plan is to stick enclosure on the back of the iMac on some 3M tape. What I have: 60Gb Mushkin SATA2 SSD External USB3 enclosure for 2.5 inch disk Questions / Concerns I have regarding the setup: Is 60Gb going to be enough for Mountain Lion and some apps? (I do use it now for Windows 7 + Apps and still have 15GB fee, so not a heave apps user). Would I be able to install ML on external USB3 disk without going to Apple Store? (does apple keep OS image on some hidden partition for reinstall?) Would I be able to boot from USB3 port? Maybe someone who currently have latest Ivy Bridge MacBook or Air can confirm and did tried this before? Would I be able to configure iMac to persistently boot from external disk or will I need to select it every boot time? Will sleep/wake function work with OS on external USB disk? Another option is probably to boot from external Thunderbolt but I believe it will be more expensive than buying SSD option from Apple. Sorry if above questions are dumb, but its my first experience with Apple hardware, beside iPhones and iPads for last 4 years. Thanks!