The problem is most likely BAD OR DAMAGED SOLDER JOINTS between components and PCB...
it may be in power supply or motherboard..
please carefully check each and every solder joints, please use a magnifieng lens to observe the pcb for dry solders.
you must re-solder all the damaged joints..

The capacitor should disengage shortly after starting, if not that could cause a problem, however, not sure what your scenario is, you don't say much