yes absolutely. The differential pairs can be configured in arrays of 1,4,8, and 16. The physical size of the slot doesn't matter. A card with only a single pair designed for a 1x slot can fit into a 4x,8x, or 16x slot. It will not latch in but it will work. The converse is also true if the card is physically altered. A Graphics card with a 16x connector will work in a 4x slot if it is cut and the firmware allows it.