Sorry, I didn't notice someone replied to me until now. I have a GeForce Go 6200 TurboCache.
I'm still experiencing problems with 185.19, however I worked around that adding this to /etc/modprobe.d/nvidia:
options nvidia NVreg_RegistryDwords="PerfLevelSrc=0x2222"
This disable PowerMizer and seems to prove my hypothesis.