Dell OptiPlex 790 (Early 2011) - Manual (Page 78)

Troubleshooting
Steps
– Clear CMOS.
– Disconnect all internal and external peripherals, and
restart the computer. If the computer boots, add the
peripheral cards back one by one until you find the bad
one.
– If the problem persists, the system board / system
board component is faulty.
LED
Power Button
Problem
Description Some other failure has occurred.
Troubleshooting
Steps
– Ensure that the display/monitor is plugged into a discrete
graphic card.
– Ensure that all hard drives and optical drive cables are
properly connected to the system board.
– If there is an error message on the screen identifying a
problem with a device ( hard drive), check the device to
make sure it is functioning properly.
– If the operating system is attempting to boot from a
device (optical drive), check system setup to ensure the
boot sequence is correct for the devices installed on
your computer.
Beep Codes
The computer can emit a series of beeps during start-up if the display cannot show
errors or problems. These series of beeps, called beep codes, identify various problems.
The delay between each beep is 300 ms, the delay between each set of beeps is 3 sec,
and the beep sound lasts 300 ms. After each beep and each set of beeps, the BIOS
should detect if the user presses the power button. If so, BIOS will jump out from looping
and execute the normal shutdown process and power system.
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