Thanks for the tips. I switched to the beta and no joy.
I then hooked up my monitor directly to it instead of the GTX670 and it works. now So it looks like an issue with the dummy plug I am using (made my own based on overclock instructions). Unfortunately, I have no idea how to tell if the dummy plug is properly being detected and works as I am able to mine on the R9 regardless of whether its hooked up to a dummy/monitor.
I have the exact same issues you have. I didn't consider it could be the plug. I just have a spare DVI cable plugged into my second card, but I don't get any temperature readings in GPU-Z, and I can't change any settings in MSI Afterburner. I have an XFX R9 280x, but seem to have the exact same problem as you.
Someone linked this in another thread, I'm going to try and build one;
http://www.overclock.net/t/384733/the-30-second-dummy-plug