Switched from cgminer3.9 to 3.10 and managed to overclock to 52:2:950 with much less hardware errors and no asic timeouts. Now it averages at 21.5gh/s. Temp is about 36°C.
At 53:2:950 the hardware errors are way over 20%...
i see there is also cgm4.0 now in
http://ck.kolivas.org/apps/cgminer/