So I had a very pleasant surprise today when I flashed the latest Maximus 6 Impact UEFI/bios (rev. 1603, released 12 September, 2014.) Asus has added an option in the advanced CPU Power Management configuration to disable MSR lock, thus enabling native CPU Power Management in OSX without a kernel patch, or patched UEFI. This was previously introduced in their Z97/9-series motherboards, and I honestly never expected them to back-port the option to Z87, so I’m impressed!
I’ve just finished some quick testing to make sure that power management, sleep/wake, etc. all still work with Clover without the “AsusAICPUPM” or “KernelPm” settings enabled, and I’ve updated the config.plist on my main hackintosh page accordingly.
So, anyone out there with an Asus Z87 board, check your relevant support/downloads page to see if you have a recent bios update. Here’s the page for Maximus 6 Impact users.