Windows cannot find Nexus 9 at all

So I have a stock Nexus 9, haven't rooted since unboxed, and I've come across a problem. I want to root it, but when I connect it to my PC, it doesn't show any sign that it's even connected. There's no sound or anything. I can't find it at all in the device manager, not even with an obscure name. There isn't even any sign of connection on the Nexus 9 other than the fact that it's charging. It doesn't even bring up options or anything. I've tried everything, from disabling USB debugging to rechecking "MTP Device". I used the same cable with my Nexus 5 and it works perfectly, but it doesn't seem to work with the Nexus 9, nor does the stock cable. Please help!