Additional info: rereading the mobo manual, I realized I had plugged the HDs into SATA 3 and 4. When the C: drive is connected to SATA 1 and to SATA 2, the machine doesn't even get as far as the BIOS.

What does No bootable image found notebook will be shutdown mean? If your computer is unable to boot as there is no bootable image found, your Boot Option or Mode or ...