AMD Driver signing.

This for me, is the biggest problem when setting up a rig with AMD GPUs. I thought for a long time that I'd bricked my cards but I did some research and found that the code 43 error in device manager was due to the drivers not working.
This is the best fix that I can find.

For win 10:
Download the modified kernel driver here: http://bit.ly/2h0NpwR
Download the Pixel Clock Patcher here: https://www.monitortests.com/forum/Thread-AMD-ATI-Pixel-Clock-Patcher (needed for the windows driver signature workaround)

1. Navigate to the amd driver extraction directory, usually "C:\AMD" then go into" Win10-64Bit-Radeon-Software-Crimson-ReLive-16.12.1-Dec7\Packages\Drivers\Display\WT6A_INF\B309333"
2. Extract the modified kernel driver in the "\B309333" directory overwriting the file
3. Uninstall current amd drivers normally and DO NOT REBOOT when asked
4. Reboot with advanced options like so:
5. Press and hold the Shift key on your keyboard and click the Restart button.
6. Choose Troubleshoot > Advanced options > Startup Settings and click the Restart button.
7. When your computer restarts you’ll see a list of options, press F7 on your keyboard to select Disable driver signature enforcement.
   This is needed only ONE TIME to successfully install the modified kernel, in the next reboot the driver signature enforcement will return to normal.
   8 ) Install the driver normally with setup.exe in C:\AMD\Win10-64Bit-Radeon-Software-Crimson-ReLive-16.12.1-Dec7
   DO NOT REBOOT WHEN ASKED
8. When the installation is finished run the atikmdag-patcher.exe (this will take care of driver signature for windows so we no loger need to disabled the enforcement with F7)
9. Press yes to patch the file
10. When finishes reboot the pc and enjoy your modified bios

This was taken from BitcoinTalk
https://bitcointalk.org/index.php?topic=1806196.0