How can it be coming from your CPU but you think it's power supply? Do you just mean computer?
Anyway, was this system custom built? Did you buy it from a company like Dell? What brand of PSU is in there?
EDIT: Also, have you dusted it?
i don't know more about computer hardware.
yes my system is custom built...
i checkout my psu and this is written here.
ATX/EMI filter/Auto fan