Monitor remains black at boot-up
I have 2 identical 2006 Mac Pros. All went well when one day, upon boot-up, the monitor remained black. Thought possibly bad graphics card, so replaced it from the other. Still black screen. Same with RAM, and than re-set PRAM, and start with disconnecting peripherals. Still black. Spoke with Apple people, and told may be bad logic board. Before deciding which direction to go or take, is there anything else that can cause a black screen at startup?