a lot wont go above 3.8 well the earlier ones anyway.
also some people will say a 5 loop 5 min bench of something is stable where as someone will say a 24hr run of something is stable.
mine does 3.9 something stable early c2 but needs 1.5v so i just leave mine a 1.4v @ 3.7 24/7 as i dont think its worth the extra heat voltage for 200mhz.
Mine is an early C2 also and runs stable as a rock at 3.9 at 1.52v, even in this weather it only reaches 52C at load.