If you are experiencing problems with your Dell computer, you need to first troubleshoot the front I / O panel to confirm the it is good before proceeding to more complex and expensive repairs, such as the power supply or motherboard. The I/O panel contains the switch, a diagnostic LED and sometimes even USB Ports. Perform the following test to confirm the panel is good in a no power situation.
Performing the Dell I/O Front Panel Test
To perform an I/O test on your front panel, remove the cable that runs from the front panel to the motherboard. You can unplug this on the motherboard side for easy access. Next, remove the CMOS battery.
If the system powers on, you have a bad I/O panel and it will need to be replaced. if it still doesn’t power up, you next need to troubleshoot the power supply itself, and then the motherboard last.
You can quickly test a power supply issue by jumping the power supply’s Power OK lead to a ground using a paper clip. The Power Ok lead will be the only green lead on the Power supply. You can also buy power supply testers from your local repair or electronics shop.