Aporte original por: Adam Baldwin ,
No, it shouldn't be a problem. I've got a hard drive I use with a USB adapter that I use to boot everything from old Macbooks to new iMacs (using the Option key at startup) and never have a problem booting. What I would do is try to figure out which SATA port is the main one (SATA 0 usually) and plug the SSD into that so that it boots from the SSD first. Otherwise, you could just plug the SSD in, turn it on and immediately hold the Option key to get the boot menu and select it from there. You should have zero trouble booting from it.