This allows for you to set advanced options, such as disable Intel ME (temporary disable mode), change option ROM load policy (legacy vs. EFI OROM load first), change Azalia HD Audio Controller Power Management Mode (PME Disabled required for Windows XP audio to work on boot), XHCI Handoff Enable/Disable, etc. Here's how I entered the advanced mode: 1. Turn off the computer fully (not fast shutdown). 2. Press the power button to turn on. 3. Immediately press and hold CTRL key, then repeatedly press DEL key (or other key required to enter BIOS e.g. F2 or F10). 4. Advanced BIOS menu should appear (menu will say your access level is Administrator). Tested working with Acer Aspire XC-704G Desktop PC.