-w 256 -g 1
I don't think you need to specify a work size with those GPU's, not sure though since I don't have those.
Why are you limiting your GPU's to one thread? I would remove both of these settings.
Sam
I tried it without them, same story. It's like GPU's not working on their full power (this config worked in windows, hardware is ok, linux is more stable).
I don't know is there some settings how to configure GPU usage.