Position #1. the standard design is when odd is ejected, the tray faces away from front IO ports.  when you have headphone or usb devices plugged in FIO, the tray should face away from FIO so there is no interference of loading disc.  also, the odd eject button is by standard placed to the right side of tray when the tray is facing up. you do not want the tray to be facing down which would be the case in position #2. PS in vertical position the Dell logo is supposed to be up right and not upside down. [IMAGE]  
In which position does the optical drive receive the optical disk from above? In position #1 or position #2? Position #1 [IMAGE]   Position #2 [IMAGE]
Placing Optiplex SFF horizontally on a shelf