Are you a first time HD user.
You have to be VERY careful with those cards. There are very small things just at the end where it would slide into the holder on a mac , and those can be sheared off very easy.
It is possible to have a bad card ,its probably used so its possible. Have you made certain the connection from one card to the other is good. Do you have them in the correct slots. Core at very bottom ,(usually above graphics card)and accel above the core card.
Can you run digitest with just the core card. Digitest is not 100% accurate all the time a lot of people cards don't always pass digitest and there is nothing wrong with them. Try downloading the newest version of digitest and try that.
You don't sound like a dumb a*s so you probably just have a bad card. If yours is under warranty AVID is super great at getting those back to you fast.
If its not under warranty you can buy them used from AVID resellers for $600 so it at least won't cost a fortune. Keep your fingers crossed
