But making sure heat production is kept as low as possible is only part of the equation, as mentioned AMD processors have other features that Intel’s lack. The 600 series, like the 500J series, includes support for the Execute Disable Bit, which first debuted on the desktop as the No eXecute (NX) bit on AMD’s Athlon 64 processors. When using Windows XP with SP2 it can be used to help minimize the risks of certain types of security threats, such as buffer overflow exploits. Naturally it is also supported by other operating systems, to a similar end. The 600 series also included support for 64-bit extensions, which Intel dubbed EM64T, for Extended Memory 64 Technology, but in essence they’re similar to AMD's AMD64 extensions, which have been included with every Athlon 64 and Opteron processor that has shipped over the past few years. One of the biggest benefits of using these processors with a 64-bit OS will be the ability to use more than 4GB of memory, other than that 64-bit support does not bring extra performance per se.



The small Intel heatsink shipped with 500 series Pentium 4 processors
So these features do nothing to up the performance of the 600 series, they just add features that, after the introduction of the Athlon 64 in 2003, bring the Pentium 4 on par with AMD’s processors. But there’s more; the 600 series processors feature 2MB of L2-cache, which is double the size of the 500 series. Manufactured with Intel’s 90nm process the roomy 2MB cache meant the transistor count for the 600 series was increased to 169-million as opposed to the 500’s series 125-million. Obviously this also meant a bigger die-size, to make room for these 44-million extra transistors, which increased from 122mm^2 to 135mm^2, resulting in an 11% increase in die size. In the past an increase in cache memory has caused for a healthy increase in processor performance for Intel, so moving to 2MB L2-cache could turn out to be well worth it.



The large Intel heatsink shipped with 600 series Pentium 4 processors
Besides the 600 series Intel also launched a new member of their Extreme Edition processor family today, the 3.73 Extreme Edition. This processor is based on the same core as the 600 series, thus also offering 2MB L2-cache, but lacks the SpeedStep and TM2 throttling features. Operating on a 1066MHz FSB, and thus requiring the 925XE chipset to work, this processor promises to offer the pinnacle of performance, although not at a small price. Previous Extreme Edition processors were based on the 130nm Gallatin core, and featured 512KB L2 and 2MB L3-cache, thus the 3.73 EE will be the first to omit the L3-cache in favor of a larger L2-cache. This will make the 3.73 EE basically identical to the Pentium 4 600 series, but for the slightly higher clock speed and the support for the 1066MHz, we’ll have to see whether that’s enough to justify the higher price tag.