The Thunderbird core had more heat and heat related issues than the Palomino core. I use a Thermaltake Volcano 7 on my XP 1900+ and always run under 42 C even when maxing it.. The same on my old 1.2 Thunderbird would yeild low 50's... Even the newer P 4's have has some heat issues.... But then the stock fan and heat sinks on AMD aren't really that good anyway....I wonder how the clawhammer 64 bit processor is? I still think G5 (as well as G4 and G3) are much cooler anyway 8-)