You'll need the classified tool most likely to push the core harder without crashing. It's a simple tool that allows you to move sliders similar to PX1 or MSIAB and increase voltage to different power controllers in the card (for mem, core, etc). I have a limited understanding of this myself, but there have been posts here and also on overclock .net about it and where to start.
One more line item down on gpu-z shows the "limit" reason, which would be helpful to see, but its probably limited due to voltage constraints. A good place to start would be changing your NVVDD to 1.125 in the classified controller and try it again. Others here will surely chime in with more detailed information, but when I did this, I was hitting 15k+. Good luck!
Edit: I'm also seeing some of these runs with the PL at 111%. That's another issue. I did see a run with the 120% which is correct, as I believe its 120.9% but MSIAB doesn't round as PX1 does.