28 Quick Reference Guide• If the power light is off, the computer is either turned off or is notreceiving power.– Reseat the power cable into both the power connector on the back ofthe computer and the electrical outlet.– If the computer is plugged into a power strip, ensure that the powerstrip is plugged into an electrical outlet and that the power strip isturned on.– Bypass power protection devices, power strips, and power extensioncables to verify that the computer turns on properly.– Ensure that the electrical outlet is working by testing it with anotherdevice, such as a lamp.– Ensure that the main power cable and front panel cable are securelyconnected to the system board (see "System Board Components" inyour User’s Guide).• If the power light is blinking amber, the computer is receiving electricalpower, but an internal power problem might exist.– Ensure that the voltage selection switch is set to match the AC powerat your location, if applicable.– Ensure that the processor power cable is securely connected to thesystem board (see "System Board Components" in your User’s Guide).• If the power light is steady amber, a device may be malfunctioning orincorrectly installed.– Remove and then reinstall the memory modules (see "Removing theFront Panel" in your User’s Guide).– Remove and then reinstall any cards (see "Cards" in your User’s Guide).• Eliminate interference. Some possible causes of interference are:– Power, keyboard, and mouse extension cables– Too many devices on a power strip– Multiple power strips connected to the same electrical outlet