After reading literally hundreds of threads and trying every driver under the sun. I have the found the offending issue causing my r9 290x black screening on boot up. If I disable CCC I do not get black screens. If I reenable CCC it black screens on boot. I have tried tried drivers going back to 13 something. Some CCC work better but still black screen. Anyhow if your having this issue with your card try disabling CCC.