Because this is an OEM board, the BIOS is customized for Medion/Windows Vista/7 systems. The manual explains the exact key sequence (Del for BIOS, F11 for boot menu, Alt+F2 for BIOS flash).
Thanks in advance!
Go to ftp.msi.com.tw → Motherboard/ → OEM/ → MS-7613/ → Manual/ → 7613v1.1_manual.pdf . ms 7613 ver 11 motherboard manual link