According to: http://www.blackmagic-design.com/support/detail.asp?techID=177#graphics Matrox graphics cards are not certified for use with Intensity cards and are unsupported.
So as I understand, it's impossible to use Parhelia along with Intensity card??
David, could you comment it?

We haven't tried that combination. If the opportunity comes up QA will investigate, but that might take a while so hopefully someone else can report on this.