A Japanese web-site revealed some information about heat-dissipation of Intel Prescott processors due to come this November at $637 price-point. The chip will be extremely hot and hungry and in general this is a reason why it will not be compatible with the vast majority of i865 and i875P-based mainboards that were meant to be compliant with the Prescott.
Despite of the fact that the code-named Prescott will be made using 90nm fabrication process using Intel Strained Silicon technology, the babe will be very hot and will eat loads of electricity. According to this report, the Prescott 3.60GHz processor's Thermal Design Power will be about 103W, 15% more from initial expectations of 89W. A version of Prescott processor for DTR notebooks will typically dissipate about 94W heat.
In order to meet such requirements Intel also had to increase the current for such CPUs, and that is an explanation why the most of current mainboards will not be able to work with Intel Prescott processors. For instance, the original Prescott 3.60GHz was intended to work with 78A IcccMax, whereas the real version will only be able to function with current increased to 91A.
News source: X-bit labs