B0: I switched it off, because in turbo mode all cores receive increased voltage, but only one is clocked up. 3.5 GHz 1.375V is stable with cpu stress only. When the full system is stressed, 1.41V isn't enough ( the voltage isn't stable, overloaded supply), and the sys fan can't handle the situation ( max. 93°C reached). A desktop with better cooler and more robust power supply should work at 3.5 GHz.
It seems, that +50mV/100MHz is necessary above 2.85GHz, so probably 4.0GHz @ 1.65V may be reached at a desktop. Now I try to get an external cooler.
About stability: my settings were tested with cpu load only for 1 hour. According to my tests (prime95, aida64, performance test v7) at 2867 MHz I have to add ~50 mV to get stable system at full load (cpu+gpu+ram+hdd stressed). Yesterday I had one adobe plugin crash with the original voltages.
Don't worry about temperature, you have a desktop cooler. Extended industry range is from -40°C to +105°C. Most cars are running with an engine control unit at 85..90°C. Anything below 90°C is fine. link
edit2: they achieved 3712.5 MHz stable at 1.5V on A8-3850. I would need something around 1.42V for 3500 MHz stable, and +50 mV per each 100MHz. Almost the same voltage levels at same speed. link2Edited by doom3d - 1/28/12 at 8:59am