The BIOS, or System Setup program, maintains your Dell Latitude E4300 laptop's hardware configuration. If you replace the motherboard or some of the components that are directly attached to the motherboard, such as the processor, the graphics card or the coin-cell battery, the computer may lose its hardware configuration and it won't work. You'll have to go into the BIOS to set up the hardware configuration to get your computer back on track. To get in, you have to press a single key at a specific moment when the computer starts up.
Start or restart the computer.
Wait for the POST screen (the screen that displays the Dell logo) to appear. The POST screen displays the prompt for entering the BIOS.
Press the "F2" key on the POST screen, but before the Windows logo appears, to enter the BIOS. If the Windows logo appears, you'll have to restart the computer and try to get into the BIOS again.