No function motherboard

i hope u r a professional in handling viz assembling/disassembling pc(s)..and assuming that the bios has not been flashed in a wrong way..probably itz either a case of loose ram/board short/improper ground/cmos battery..plz do check the following as in order:..

1) see if the ram(s) is loose/faulty..open clean/remove carbon & or oxide formed on the teeth with an eraser n resit it..

2) unplug mains supply..pick open/remove the cmos battery..check (above +3v)..resit..

3) remove/clean dust neatly..dust is non-uniform in nature n may cause jam/short circuitry/excess resistance n many more..resulting an increase in heat..

4) open the CPU Heat-Sink with fan out of the socket..put some "Heat Sink Compound" (available in local electronics chip level spare market) between the cpu/processor and the CPU Heat Sink *** fan..resit/fit it tightly in position..

5) the smps itself may b defective/faulty..check the outputs of smps viz. 0v (black~ground); +12v (yellow); +5v (red, green~ps-on, violet~pg & grey~sb); -12v (blue); -5v(white); +3.3v(orange)..
the 'oscillator and error amplifier ic', or pwm switching regulator circuit..look for defective protector-transformer/resistance(esp 4.7k)/mosfet..

6) if itz not the smps, then it must b ur main/mother board..see with a debug card for mb error..may b short..look for defective capacitors(esp above 1000mfd)/mosfets..go through the mb's south bridge n the circuit lie around atx connector....

always better to seek advise from ur system admin/vendor....