Set the BIOS Mode
The BIOS firmware supports both legacy boot mode and Unified Extensible Firmware Interface (UEFI) boot mode.
The default setting is legacy boot mode. Some ESXi installations supports both legacy boot mode and UEFI boot mode. You must set the BIOS to either legacy boot mode or UEFI boot mode before you perform the OS installation.
Note - If you are performing a VMware ESXi 5.5 installation over a network, UEFI boot mode is not supported. You need to use legacy boot mode (the default).
 | Caution - Possible system failure. Changing the boot mode after installation might make the disk drive unbootable. Depending on the boot mode at OS installation, you can create an incompatible boot disk format. |
- Power on the server.
POST messages appear on the console.
- Watch the messages, and, when the prompt appears, press F2 to
access the BIOS Setup Utility.
The BIOS Setup Utility main screen appears.
- In the BIOS Setup Utility, use the left or right arrow keys to
navigate to the Boot screen.
The Boot Menu screen appears.
- Use the down arrow key to select the UEFI/BIOS Boot Mode field.
- Press Enter and use the up or down arrow keys to select the Legacy or UEFI BIOS option.
- To save the changes and exit the BIOS Setup Utility, press F10.
Next Steps