The Pentium 4 500 Series, Continued

With the introduction of the new socket LGA775 in 2004, Intel announced plans to ship a 4 GHz part. This announcement was retracted later that year. With the 500 series, Intel reached a maximum clock speed of 3.8 GHz.

Pentium 540 running at 3.2 GHz

No more pins: The back of a Pentium 540

Many features that had been present in AMD's Athlon 64 CPUs were subsequently activated in or introduced into the 500 series, albeit only after Intel had introduced the new 600 series of the Pentium 4 family. One of these improvements was Enhanced Intel SpeedStep Technology (EIST) , which allows the CPU to automatically lower its multiplier to 14x (2.8 GHz) and its core voltage from 1.4 V to 1.2 V, lowering the processor's thermal power loss. Additionally, the C1 feature was extended to C1E, which is required to activate the EIST functionality. Still, even a measured minimum power consumption of 23 watts is seven times higher than what is possible with AMD's Cool & Quiet.

Another new feature is the Execute Disable (XD) function. It corresponds directly to the NX feature previously introduced by AMD.

Lastly, in February 2005 Intel also implemented 64-bit functionality ; this was originally introduced by AMD into its own chips under the name EM64T ; AMD began offering this feature ion September 2003.

To differentiate the new models with the additional features from the previous ones, Intel appended a J or a number 1 to the end of the model number, as the following tables show.