In order for the dreamcast to boot, it requires only the motherboard, the disc drive (or ODE), and the 3.3V / 5V rails connected. No front board or 12V rail are required (the 12V rail is only needed for the disc drive to work, but not required to get you to BIOS menu).

The following is a list of things that need to be functional in general for your console to get to the boot menu.

• Working power board able to supply required current on 3.3V and 5V rail
• Connection between power supply and motherboard must be clean and solid
• The 3.3V rail should draw between 2.0A to 2.7A
• The 5V rail should draw 0.6A
• BIOS must be fully working, soldered well, and no torn traces
• Connection between disc drive/ODE and motherboard must be well fitted and clean

Black Screen

A black screen, or intermittent boot to menu (sometimes boots, sometimes doesn't) is often the disc drive connection is poor. This is a very weak connector and even removing the disc drive a few times during service can be enough to prevent good contact and failed boot to menu.

Dreamcast Disc Drive Connector