I'm happy to report that I've finally got reaper running successfully at high speeds with very few stales. I now get 454Kh/s or above on my HD6950 (unlocked to 1536 shaders) with these settings:
and in reaper.conf:
Adding 'device 0' is very important as this stops reaper from mining on CPU and GPU which degrades performance.
Clocks are (stable at):
885MHz (core clock)
1000MHz (mem clock)
Great success.I hope this thread helps those who need it.