My I mac not support booting by External drive and Not Find Bootable USB ,
in the past time i use bootcamp with same prosses in this time but after first boot make partition and biling a ------ and Problamb show not find ...BOOTMNGR
i try saveral time and also upgrade all soft and new External CD Drive but no solution
iMac (27-inch Mid 2011), OS X Yosemite (10.10.5)
