Desktop would not boot

hi,

i changed my desktop pc motherboard recently and my system was running on windows xp however i only used the new motherboard for a week and left the system down for about a month and now im back but the system wount boot.
power is goin to th? board, all fans working,and all led lighting, cd tray opening, but not booting.
usually there is a "clicking" sound before the system boots but now no sound.
i remove the memory n boot n i got the memory beeps, install them bk in n no boot still.
help please!!!!