Please follow below steps to configure your BIOS. Then RTC Alarm should work on your board.
1. Disable "EUP Function" of "Power Management Setup" like following picture.
(Note: it's a must to disable EUP if you intend to enable RTC Alarm on the board.)
2. When setting "Resume By RTC Alarm" to [Every Day] as bleow screenshot,
3. Please specify the time in below items you hope to turn on the system (in this example the time is set to 00:03:00.)
4. If you set "Resume By RTC Alarm" to [Enabled] as below,
5. You must specify which day & when you like to turn on system (in this case, we set it to Day 1, 00:03:00. So system will automatically power on at 00:03:00 of the 1st day in each month.)