As above, there are a lot of possible causes. Some basic things to try:
- try another wall outlet for your power. Preferably in another room.
- try another power cord
- check the power-on button. It may be bad or the wiring is loose/intermittent.
- if there is a setting for voltage on the back of your PC (110/220) make sure it is correctly set for your area.
- hold the power button in for several seconds, if it is button. If it's a toggle switch, never mind.
- make sure your PC power management configuration is correct. It may be in some sort of sleep/hibernation mode.
- there should be no 'warmup' time with your PC. If it behaves as such, then you may (also) have a bad power supply or intermittent connection on your main/motherboard.
All of this is guesswork without some knowledge of what you are using and how (PC/hardware models, changes made or problems when this occurred, etc.).
- does it always behave this way?
- when it finally works, is everything normal?
- any other info you think might be related?
Dell