I can definitely confirm this, I tried to air cool my 5950X without much luck. Enabling PBO I've seen it go over 200W, which a 240mm rad handles very well.
Huh. Interesting. I put a noctua heatsink (dual fan) on mine but I am guessing this is why my overclocking curves weren't that great. Any chance you have the rough before/after numbers and how much did you splurge for the water cooling?