This worked for me as well! After sending back the first RX460 and then trying a different model from a different vendor I finally got it working! Thanks so much helpfulnobody!
Recent AMD GPUs have a hybrid firmware that causes problems for some early (2010-2012) UEFI “compatible“ motherboards. They try to load the UEFI GOP driver on the GPU and fail, leaving you stuck with a blank screen at boot.
If if you are lucky there is a firmware update for your motherboard or a BIOS menu setting to force legacy vBIOS boot mode that will resolve the problem.
If you don’t have that option you can still work around the problem by editing the firmware of your GPU to hide the GOP driver, thereby forcing your motherboard to use a legacy vBIOS boot mode. I‘ve done this on an RX 480 that would fail to boot with an Alienware Aurora R3 from 2011.
Note hex editing your GPU bios is risky, make a mistake and you will brick the card.