Q: AMD Radeon R9 M370X not recognized by Windows 8 partition. Mid 2015 15 inch Macbook Pro

Can you run msconfig and check the installation mode? Is it UEFI or BIOS?

Do you have any unknown devices in Device Manager with yellow triangle and exclamation mark? Can you try to install W8,1?

Please execute the following two procedures...

Resetting the System Management Controller (SMC) on your Mac - Apple Support

How to Reset NVRAM on your Mac - Apple Support

and then try to boot into Windows and see if you can see any devices which require drivers.

I'm having a similar issue (same machine type, no graphics driver options), but am stuck on the upgrade from Windows 8 to Windows 8.1. The Windows Updater says that I need to restart Windows to complete upgrades. I've done 4 restarts and it still says the same thing (must restart to complete upgrades). The Microsoft Store tells me I can't install Windows 8.1 because Windows Updater still has updates to make.

The boot camp installation went fine, so I BELIEVE that it picked up and installed the current drivers.

Any advice on where to look to solve this loop?

Run the SMC Reset and NVRAM Reset and then download drivers from System requirements to install Windows on your Mac using Boot Camp - Apple Support for your Mac and Boot Camp: Install or repair Boot Camp drivers .

Thanks for your quick reply. I did both resets, downloaded fresh drivers using Boot Camp Assistant and reinstalled them per the instructions on the websites you gave me, but I'm still having the same issue. Windows Updater insists that the machine needs to restart to finish the updates, but it never seems satisfied! After multiple restarts, it still says the computer needs to restart. It doesn't give me any clue as to what needs to be updated.

I actually did the SCM and NVRAM resets twice and downloaded the drivers twice with Boot Camp Assistant. Same results.

The Mac OS is 10.10.3, Boot Camp Assistant is version 5.1.4. I'm starting to dive into every FAQ and article I can find, but any additional ideas would be appreciated!

Can you run Windows Update and check for any remaining updates or failed ones?

Windows Action Center says that I need to download and install a driver update for Boot Camp, but it's not specific on the particular driver. I'll reach out to Apple Technical support to see what they might be able to suggest.

Either you're clairvoyant or I did something. Formerly, when I went into Windows Update all it said was that I had to restart. Now it tells me there are 141 updates to install and it also shows me a button for checking for updates. No other options are present, though. It tells me these updates will be installed automatically. I'm looking for a way to see what they are or to run them now.

I am not clairvoyant yet.

Be careful with Driver Updates. Avoid these if you can.

I don't see any driver updates in the list. Am running this now and will see. Fingers are crossed.