step by step troubleshoot
1)open your cpu
2)disconnect your psu from all devices
3)Smell the cpu(not funny, this is to check got burn or not, if got
surely got burned smell)Don't have? move to the next step
4)Power up your psu; just plug the cable into direct power source,
should be able to on. Cannot on? put aside.
5)take other psu and connect all the wires on to your motherboard
and try to power it up. Cannot on?, your psu is safebut your
motherboard isn't, if can on your psu dead liao;need to
change
6)If you have any other extra mobo, try to turn it on using
your(working psu). If cannot, mobo dead, need to buy new
mobo.
Hard disk or other problems
1)Turn on your pc, if it hangs or crash, most likely a virus or
some conflict.
2)If got several beeps means one of your hardware is dead
3)disconnect all hardware(do not disconnect your psu from your
mobo) and plug it in one at a time(plug in one device and see if
can turn of without beeps), Don't have beeps, proceed to other
devices. If after a particular device you plug in got beeps, take
it out, and continue with other devices. The ones which you plug in
got beeps means that its faulty.