Dell Inspiron 7577 HDMI output

For my recently purchased Dell Inspiron 7577, I found another issue with HDMI output. The problem is that, when I connected to my external monitor (ASUS PB278) via HDMI cable, there is NO signal during the boot process of computer, which means that I cannot enter bios, select boot devices, etc. using external monitor, since I CANNOT see it.  However, the signal indeed output starting from the login screen of WINDOWS 10. Has anyone encountered the similar problem? Can someone in DELL help me? Thanks!