I have seen this before. Some cards are not completely compatible with some motherboards. I have actually seen this documented in some card's user guide, though I cannot recall which one at this moment. In that same user guide there were some conditions for some motherboards, in some, it would only work in odd slots, in some only in even slots, in some you had to have a graphics card in, in some you had to not have a graphics cards in, or something to that effect. So try different slots, else you might just have incompatible hardware - meaning new motherboard, or tuner...