Raaboso,
First off, there is no way a comparable speed t-bird(or in your case, faster t-birds) are cooler than p3s. herein lies hte first problem, socket-a boards do not measure core temp, and some boards do not measure even close to core temp.
Secondly, Socket-thermistor readings from Super/Chrome Orbs are highly suspect, as they do something to effect socket-thermistor readings. One might ask, how are they effected? Very simply, even aiming a can of compressed air at the socket-region for 1 second will drop the reading 4C. Flip it upside down so that condesnation forms, and the reading drops 6C.
Thirdly, it looks like you're using an MSI board. THese boards typically under-read temps 12-15C, if not at times much more.
Lastly, even AMD doesn't suggest using socket-thermsitors to test heatsinks. And there is a reason that hte palamino core will finally have an internal diode.
MIke