Now that we have a basic grasp on the different operating modes and changes made to the IA-32 architecture, let us now take a look at some of the advancements made with the latest “Prescott 2” core. The main difference between the 5xx and 6xx series of processors is that Intel has upped the L2 cache to a full 2 MB, along with adding Enhanced SpeedStep Technology, EIST, support. Intel’s EIST offers power saving similar to what is currently being utilized in the Centrino line, and allows the OS (WindowsXP SP2) to control when EIST is enabled and disabled based upon the current system load. This technology should help keep down the heat a little better on the “Prescott” core Pentium 4’s, well known for their ability to heat up a room.

     When it comes to the 3.73GHz Extreme Edition processor, quite a few changes have been made. This is the first Extreme Edition processor to be based off of a “Prescott” core. Intel has done away with the Northwood core now for good with the latest Extreme Edition. With that loss, comes 2 MB of L2 cache versus the 512MB of L2 the Northwood core allotted. Intel has also chosen to do away with the 2 MB of L3 cache, and does not offer support for EIST. This poses and interesting question, what is the difference between an Extreme Edition and a normal 6xx Pentium 4?

     The answer is quite simple, bus speed. This is certainly going to leave Intel in a tough spot to sell these Extreme Edition CPU’s, given that the only difference between them and the 6xx processors is that the EE’s run off of a 1066MHz FSB, while the 6xx’s run off of the 800MHz FSB. Both feature 2 MB L2 cache, Execute Disable Bit, EM64T, are built on the 90nm process, have the same die size of 135mm2, and have a transistor count of 169 million. When the upcoming dual core processors debut the Extreme Edition will break away with some additional features, such as HT support for four threads, but for now the 3.73GHz Extreme Edition isn’t much more than a 6xx on frequency steroids.