sylvannia1

Hi everyone, I followed this guide for my macbook air 2013 with a gtx 660. Exactly the same and everything has been flawless. Recently i upgrade to windows 8.1 and my egpu cannot be read by my macbook. It doesnt show up in device manager and when i try to install nvidia drivers it says it cannot continue because no gpu is detected. What should i do? Would i have to follow a different guide/get different parts? Or is it a software issue?