boot - Supermicro X9DRL-iF hang up at POST screen in B2 status code with no any external device

I've just recently reboot my server to find out an memory issue. The system just hang up at POST screen with code B2 just before booting the os, and I cannot open BIOS setup either. I've did some search and according to the manual the B2 state is 'Console Output/Input devices/Console initialization and Load Option ROM (VGA, RAID, parallel ports, serial ports……)'

refer: http://www.tomshardware.com/forum/321881-30-system-boot-error

Then I unplugged both PCI-E and USB device one by one and reboot to test. After I unplugged the last device this problem still remains.

The board is new and I did not change anything before this issue occurs, so I really have no idea about it.