@simon66, go to windows device manager, do your cards show up without yellow exclaims?
My card was working fine (Sapphire Rx480 Nitro 8GB) with Claymore 9.5. After modding the bios I get the error "no amd opencl or nvidia cuda gpus found exit" and the miner stops...and yes my card shows up with yellow exclaim.
You didn't validate the bios, windows doesn't recognize the card. Anyway it's not claymore related.