How can I get sound working on Bootcamp + Windows 8.1?

Solution 1:

Navigate on your Mac to the Bootcamp application. Before this make sure you have a 8GB USB flashdrive formatted to FAT 32, Windows default. Open Bootcamp app, and install the latest Bootcamp drivers onto the USB. I suggest naming the USB to SUPPORT all caps after doing this.

Navigate to Windows Partition on boot menu. Open up File Explorer, click on you new SUPPORT drive, open up Bootcamp folder, then drivers, click on Realtek driver set up .exe, and install that (depending on your computer it will prompt you to restart it or not after installing). Next after rebooting or re-installing the Realtek driver, head into the Cirrus folder.

This is the most important part about getting the sound to work

Click on the second .exe driver manual download, and run it. If you don't do the second one first, it won't work. After the download is complete, click on the first Cirrussetup.exe and install that. After that is complete, when you go to test your Mac's sound, there will be a slight delay... followed by the nice obnoxious chirp on Microsoft's sound test.

Sound working on Windows 8.1 x64 at 10:50, 2/21/2015

Solution 2:

Forget EFI and install using boot camp assistant.

After backing everything up, wiping my partitions, and installing Windows 8.1 using Bootcamp, everything works as normal. The machine boots using bios mode, Cirrus Audio was properly installed after a single run of setup.exe from the Bootcamp support software, and the device is recognized properly as VEN_1013 DEV_4206 --Cirrus Audio CS4206B (AB 82).

It sucks, but it's worth it. I plan on resizing windows' ntfs partition and booting linux beside it, but that's a problem for another day.