I tried 10.12.4 Beta 1 tonight on my Mac Pro and saw black screen. Apple removed AMD9500Controller.kext which had contained PCI ID and drivers for 67DF devices. The replacement kext is AMD9510Controller.kext which only has PCI ID 67EF and nothing else. Remote Access doesn't seem to work because it shows the Mac is stuck at the login screen. I swapped an RX 460 in and was able to boot into the Desktop. The kext mod prior to 10.12.4 was to enable hardware acceleration for Polaris 10 cards through AMDRadeonX4100.kext. We now need to add 0x67DF1002 to both info.plist files in AMD9510Controller.kext and AMDRadeonX4100.kext. If you feel adventurous, try updating to 10.12.4 with @HaggSpart's instructions. Here's the full instructions by @applCore to update macOS without restart then edit the kexts.