@Dante4 thanks for your tip, I tried the blind f4-enter-f5-enter combo, but it does not work for me 
(latest bios, I set serial console in bios, hdmi output does not work anymore)
@Dante4 thanks for your tip, I tried the blind f4-enter-f5-enter combo, but it does not work for me (latest bios, I set serial console in bios, hdmi output does not work anymore)