Ahh alright then.. However I never quite understood what the x4 slot was used for? Possibly sound cards?
Believe it or not they actually make video cards that are for a x4 slot and yes you can use sound cards there as well. I have an OCZ RevoDrive that requires a x4 slot and if the back end of the slot was open you could put a regular video card in there. Thw performance would be a little less but not as much as you would think. There are also raid cards that are for the x4 slot.