I suggest checking here:
http://redd.it/29mzytunfortunately i dont have a 280x for setting up but it really should be the exact same as your previous settings. I am trying to get some configs together so I can make a thorough post but I want to assure I have a lot of different algos and accurate results. Either way that reddit post has the modified cl files and I have had reports of improved hashrates with 280x (and generally fixes issues with x11/x13 not working with 14.6 drivers)
i have already checked your post in reddit, and i am still confused, GGin told me just upgrade my AMD to 14.6, but in your thread in reddit it should replaced the cl file, so which one is right? and you just tell a few parameters
"thread-concurrency" : "13188",
"rawintensity" : "131088",
"gpu-threads" : "2",
"worksize" : "64"
how about others? can you give the detail? i have both r280x and r270x GPU.
MUCH THANKS!
unfortunately im still unsure if these specific settings work for 280x. they will work good for 270x though. That should be the only settings you need the rest of the config is not required so you can delete or adjust other settings to your liking.
As far as 14.6 drivers go I do know that they have HW errors with 270x and x11/x13 mining. So if you are trying either of these then you likely will have problems (not sure about 280x probably the same problems).
Replacing the cl file (or modifying it yourself) will fix the problem with hw errors. Not sure if you are possibly having any other issues but if you are still having troubles let me know

. Easier to catch me on reddit as well I dont check here as often.
You should be able to download the CL files and place them in the kernels folder. Then you MUST delete your BIN files from the miner folder BEFORE you start mining again. After that it SHOULD work. Let me know if you still need help

. Also let me know if it works and how well it works for you

feedback appreciated.