so can you post your stable voltages?
today I'm using those ones and seems stable:
368 MHz @ 875 mV
806 MHz @ 925 mV
can you do better?
I don't know yet, I need to be more systematic in my testing cos I am changing too may frequencies at once, so if it freezes I don't know which caused it.
But from the bit of testing I have done, I doubt I will get better than those voltages.