So I'm mostly wondering what happens here. I'm considering biting the bullet on a new build but I don't want to have any hitches. I'm using the ASRock Fatal1ty X99 Killer. It supports x16/x8/x4 if you have a CPU with 28 lanes, which is exactly the route I'm wanting to go. I've got it planned out to run two GPU's, an x4 PCIe SSD, and my x1 sound card. The problem is that before the sound card is put into play, all 28 lanes would be in use, and I'm wondering what exactly would happen. What I'm hoping is that the CPU or board or whatever decides what gets what bandwidth would just automatically make my other card an x8. That way I'd have more lanes which would give me enough for my sound card, and also allow me to get another SSD if I eventually wanted to. Will it work like that, or is there some force at work on the board that says "this slot runs at x16, period"?