Hi!, a have the same problem: inifinite loop in a Samsung NP300E4C whit El Capitan USB boot. I can´t find "-igfxvesa".... where is the prompt for type this command?, I read above that by pressing "O" you could enter the argboot, ok, but I can't find anything in the options that are shown there, someone said it was in "config2", I marked that option and it remains the same. Sorry but I'm new to doing this. Thanks for the help.