Which Is Broken The CPU or MOBO?

hi either my desktops mobo or cpu is bad. the computer turns on correctly but displays nothing on the screen. inside the case all the fans run and the hdd spins and the green light lights up but nothing is displayed on the screen nor does the cd drive opens/lights up so it could be just the cpu? not sure NOTE... show more hi either my desktops mobo or cpu is bad. the computer turns on correctly but displays nothing on the screen. inside the case all the fans run and the hdd spins and the green light lights up but nothing is displayed on the screen nor does the cd drive opens/lights up so it could be just the cpu? not sure

NOTE THAT i tried different power supplies and different monitors so im positive its the mobo or cpu

i either have to spend 20$ for a new processor or 80$ for a new motherboard so i want to know whats up. its a pentium d dual 3.4 processor, not sure about the motherboard since its a prime systems desktop.

Whats wrong with my desktop?? best answer + 5 stars to whoever is the best detailed
thanks

-Ben
5 answers 5