Weekss

Hi My PC won't boot, being working fine for years. With it switched off, the green standby light of the Toughpower 775w and the motherboard power button blinks every few seconds with a beep from the speakers and this stays the same when pressing the PC power button to boot it up. No fans power up. The system is normally on standby after a set time and this was the symptom when trying wake it up. Have unplugged the power cable, the blinking will stop after awhile. Plugging back still no difference. Is it the PSU need replacing? Suggestions would be appreciated. Thank you.