I'm running a 24" Apple Cinema Display with a GTX 960. You just need a DP to mDP Adapter. That's it. Everything works as expected. iSight, Speakers, Mic. I'm also using the display under windows and it's 100% functional as well. Even brightness and volume control work under windows. You need to install some boot camp drivers for this to work properly. I'm using an Apple USB-Keyboard for this.
For me that's actually a better Windows Setup than any other "real" Windows/PC screen. It's a shame Apple stopped making those gorgeous displays.