My setup is as follows. I have tried on both Asus X99-A and Rampage V Extreme with the exact same results. I have 2 Fury X cards in Crossfire. 16GB G skill DDR4 3000, I7 5930K, Windows 10, 8, and 7 64 all do the exact same thing. I have no USB devices attached except a mouse and keyboard. I have tried with SSD, HDD, PCIE SSD and M.2 SSD with no change.
The Fury X ONLY has 3 Drivers to work with!!!!
Single GPU tests are all Perfect!! Every benchmark and test is flawless on all Windows versions. cards were swapped with eachother in crossfire and the same issue occurs. Single card setups in any PCIE slot work fine.
Drivers were installed manually and via AMD install manager with no change in outcome.
Both motherboards have dedicated x16 PCIE slots for dual and Single GPU setups, in fact you can basically ONLY put the cards in there dedicated x16 slots if you don't want issues with the cards.
Each motherboard can adjust there PCIE slots to accept Gen 1, 2 or 3 cards if needed or have them set on auto.
Both boards have the latest BIOS versions installed.
All Motherboard Chipset and driver versions are all up to date.
All versions of windows were updated to there latest builds
all drivers work perfectly as well as the CCC app itself with one card. The instant another card is detected CCC freezes upon use and the system locks up for about 5 to 6 minute intervals. Ocassional windows messages that CCC has crashed or TDR failure, boot hang and boot up crash or the message that the device driver has crashed and has been recovered happens a lot depending on the windows version.
TDR failure..boot crash and hang can be resolved with completely disabling the ULPS on both cards. when I was able to go into CCC before a crash to disable crossfire then evertyhing worked fine.. no issues.
The moment Crossfire is enabled the entire system locks up or crashes. As I mentioned above this will happen with either card in the second GPU spot and with any of the 3 drivers to choose from and in any version of windows and with either motherboard.
Your drivers are complete garbage. since both cards work perfect on there own and the exact same issues happen with multiple motherboards, in all versions of windows and with any Fury X driver and looking at all the other issues exactly like this on this forum it is concluded that your Fury X drivers are extremely bad and will not work in crossfire at all.