This French site shared with the public some pretty interesting info. The guys claim that one of their sources, referring to some confidential document, anticipates that Pentium 4 processors working at over 3GHz core frequency will be incompatible with the today’s Socket478 mainboards.

Of course, this statement is not ungrounded. Firstly, you should remember that starting from 3.06GHz Pentium 4 CPUs will get HyperThreading technology. I assume that Intel might be using some additional reserved pins of the Pentium 4 CPUs to ensure the proper implementation of this technology. In this case the compatibility of the new Pentium 4 CPUs and the today’s mainboards comes in big question.

However, there is one more reason for the new Pentium 4 with over 3GHz core clock to be unable to work in regular mainboards. Although all today’s Pentium 4 processors are manufactured with 0.13micron technology, their heat dissipation is pretty high. As the frequency grows higher (the maximum for the today’s Northwood core is 3.2GHz), the heat dissipation will also increase. Present day mainboards were designed for CPUs dissipating not more than 77W of heat. However now Intel asks its partners to doublecheck and maybe even redesign some of their solutions bearing in mind that the Cpus will dissipate up to 82W of heat. Of course, higher heat dissipation may push mainboard makers to redesign their products not only to allow using bigger coolers, but also to increase the reliability of the processor power supply circuits. According to the today’s guidelines, the CPUs are getting 60A current, while according to the new specs, this number is 70A.

As a result, the compatibility of the today’s mainboards with the new fast Pentium 4 CPUs is really quite doubtful. However, the situation will be cleared very soon, I suppose. The first Pentium 4 from the "risky group" working at 3.06GHz is to come in Q4.