Your 960 may have came with one. You'd have to look in the box it came in, unless it came with your pc. As for the slot spacing, I don't know how your motherboard is set up so I can't tell you which length you'd need. Most skip a pcie slot so that they don't sit right next to each other and have some "breathing room" per se, but again that's something that you'd have to determine based on your own motherboard layout