I just got two GTX 780ti classifieds, and the only way for me to use my Sli finger is to put them in slots 2&3. When I did this, my motherboard's VGA Led was a solid red and did not post. The only way to get it to post is by putting a smaller card into slot 1 and running it like that. I have a z170-a mother board from Asus, and a 6600k. I do not know what to do to fix this any help would be very appreciated.