best way to get rid of computer hum mic picks it up

[feedback711]

my computer produces a almost powerful hum which is barely noticable when mixed will with music but when i do radio commercials it s clear that there is a mechanical sound behind the vocals... what is the best way to get rid of this hum

[LXNDR1]

maybe this will be helpful in some way
http://www.soundonsound.com/sos/apr06/a ... n_0406.htm
and this probably too
http://www.soundonsound.com/sos/1997_ar ... udios.html