I just purchased a Z83-F and have the same issue but only with one of my monitors:
Dell S2417DG (1440p 144Hz) - blank screen instead of boot logo and bios
Dell UP3216Q (4k 60Hz) - both the boot logo and bios work fine
With the S2417DG the screen is completely blank until the windows login screen appears.
Using the OSD of the UP3216Q I figured out that you are using 1600x1200 resolution on the boot screen.
After some digging I found out that the S2417DG doesn't have 1600x1200 as a preset display mode - this might be the cause of this problem.
For more info search for "Preset Display Modes" in the user guide of these two monitors: