When I bought my first R9 380 I tried the 15.12 driver and it yielded the same as the most recent driver. I'll try it again and report back.

EDIT: Yup, for one card the driver version made no difference... for two, the 15.12 driver now gives 210sol/s on each card and reports temps and fan utilisation for both cards (it only did it for GPU 0 last time). I should have re-read the instructions!

Thank you!