I have a Dell Dimension 5150. It would not start. No beep codes. No POST LED lights. No light in power switch LED.
I disconnected everything internal (all PCI, HDs, CDs etc.) and external (USB, monitor, keyboard, etc.) to the computer with the same result. I.e. No start, No POST, only light on the computer was the LED on the motherboard. I even removed the RAM.
So, it seemed my problem was Power Supply, Front I/O panel (includes power switch) or the motherboard.
I replaced the power supply with a new PSU. No change.
I read some forums that suggested resetting the CMOS. I was able to do this by removing the battery, waiting, re-installing and re-attempting power application. This time, the computer showed a Green LED in the power switch. POST LEDs lit up fairly randomly, and then 4 or 5 seconds later, the sequence stopped abruptly, all front panel lights extinguished. At that point, I attempted to turn on the computer with the power switch. No response.
Any suggestions? Is there a way to troubleshoot the power switch / front I/O panel? Can I bypass the front panel power switch with jumpers for testing?
Thanks,
Lance