hi i have an question about my mac pro 3.1 When i boot my macbook pro with an bootable usb stick using the option key i immediatly get an grey screen with the option my mavericks drive and an recovery disk.. But when i do the same thing on my mac pro where two screen are connected.. nothing happens ?? i noticed that the aple wired keyboard is active after the chime sound is heart so i am not able to press the option key, and the mac pro boots normally until the start up screen os shown. What am i doing wrong? needs the mac pro perhaps another boot procedure? Can someone help me out? any tips are very usefull and rated.