a system and method of assigning device numbers to a plurality of i / o nodes of a computer system . each of the plurality of input / output nodes is initialized to a common default device number . the method includes assigning a unique device number such as a unit id , for example , to each one of the input / output nodes . the method may also include determining whether any one of the input / output nodes includes a graphics port . the method may further include reassigning the default device number to a particular one of the input / output nodes in response to determining that the particular one of the input / output nodes a graphics port .