Dell OptiPlex 990 (Early 2011) - Manual (Page 76)

Problem Description A possible system board failure has occurred.
Troubleshooting Steps Remove all peripheral cards from the PCI and PCI-E slots and
re-start the computer. If the computer boots, add the
peripheral cards back one by one until you find the bad one.
LED
Power Button
Problem Description Power connector not installed properly.
Troubleshooting Steps Re-seat the 2x2 power connector from the power supply unit.
LED
Power Button
Problem Description Possible peripheral card or system board failure has occurred.
Troubleshooting Steps Remove all peripheral cards from the PCI and PCI-E slots and
re-start the computer. If the computer boots, add the
peripheral cards back one by one until you find the bad one.
LED
Power Button
Problem Description A possible system board failure has occurred.
Troubleshooting Steps
– Disconnect all internal and external peripherals, and
re-start the computer. If the computer boots, add the
peripheral cards back one by one until you find the bad
one.
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