The Dell Optiplex GX280 is a mini-tower desktop computer with an Intel Pentium 4 processor. The computer's motherboard is equipped with a BIOS utility that provides a user interface for configuring hardware settings. Changing BIOS settings incorrectly can cause performance or system problems. Reset the BIOS to restore all settings to the factory-set defaults.
Turn off the Dell GX280 computer. Unplug the power cord from the electrical socket.
Lay the computer down on its side with the back of the computer facing you and the side with the "Dell" logo facing up.
Press the release button on the bottom of the computer. Pull the side cover up to open it.
Press the unlock tab next to the CMOS battery, which is a silver dime-sized battery located near the memory modules.
Remove the CMOS battery from its socket. Leave it out for at least five seconds.
Put the CMOS battery back into its socket. Press down on the battery to engage the lock tab.
Replace the side panel. Press the panel into place until it locks into position.
Set the Dell GX280 computer back onto its base. Plug the power cord back into its socket.