Re: Claymore's ZCash/BTG GPU Miner v12.6 (Windows/Linux)
why my asus r9 280x (stock bios/no OC nor UV) got "gpu return incorrect data" error at first and then 'watchdog gpu hang opencl' error in claymore miner only? i've tested with optiminer too, but everything went no problems 
Try reinstalling newest drivers, or put your GPU into different mobo/cpu. Also try different riser.