I've got a 2007 20-inch iMac logic board with a broken internal SATA connector. I've tried epoxy, solder, etc. but I can't keep the part to stay on properly. Does OS X have to see an internal hard drive attached to continue boot, or can I have an external USB drive attached and have the system automatically boot to that drive upon startup without having to go through some special procedure? It's for a client of mine, he's old, and I don't want him to have to press a special key combination to get into his OS.