A:Answer To run sli, a new motherboard would be needed if you want two 1080 ti's. If you had a thinner graphics card, it might be easier with the correct bridge. The problem is that there is a card which I imagine is either the sound card, but more likely a wifi card with a plug in extender is in the way of fitting in two 1080 ti's with this model. So, again, yes to fit two 1080 ti's you are looking at a larger motherboard, and another 1080 ti extra.