It is a short question you ask, but I could talk hours to you about testing these products.
In (very very) short:
First there is DFT (Design For Testability) but I think you are past this milestone ?
Boundary Scan Technology is, in mine opinion, one of the best methods fot testing digital boards. But it depends strongly on the DFT.
After that it depends on the quantities, ICT test, Flying probe test. Here you talk about several k's in money terms and for ICT the DFT part is important.
BIST. Build In SelfTest is a good method for testing a board from the inside (minimal kernel of proc and program in Eprom) and extending this to other parts of the board. Difficulty here is the communication towards the operator in case of an error and fault finding. I did a lot of fault finding on CPU boards and motherboards with a listing of the BIST and a logic analyzer.
Then there is always the functional test and most people start end stop at this stage. For a motherboard I would say try to simulate as much as possible. I know there are Keyboard/mouse simulators so you (or the operator) doesn't have to do much and there are no operator errors in that part.
But when you test functional you have to have a operating system running and the Human interface must operate. So that is ? 80% ? of the motherboard.
And you can use a mix of these methods and many other things.
You replied to a 3.5 year old thread that was awakened by rickgyles.
Good info, nonetheless.
See Rick's new thread here