I have just replaced a power supply (400W) after confirming the old one (450W) was faulty. After replacement, the system is able to run normally with many rounds of reboot but it just refuse to boot after shutdown gracefully. The symptom is there is no beep sound and no video signal although the power LED shows running at the casing. I can see the fans are spinning. Strange thing is the system is able to boot again on the next day or after some hours. The same problem comes back again after shutdown gracefully. May I know could this be due to insufficient power supply? What is the probable cause if there is no beep and w/o any video signal? Many thanks in advance.
