ASROCK A780 Manual Del Usuario página 220

NOTE
If you select [AHCI] mode in the BIOS setup and plan to install OS on your
system, after the final BIOS/DOS boot time, there will be a string shown as
below.
Please ignore the instruction on the screen. Please do not press [Space] key at
this moment. Otherwise, the AHCI ROM will not initiate your SATA HDD, and
the OS installation may fail.