Prescott-256 Celeron D processors, initially launched June 25, 2004,[21] feature double the L1 cache (16 KiB) and L2 cache (256 KiB) as compared to the previous Willamette and Northwood desktop Celerons, by virtue of being based on the Prescott Pentium 4 core.[22] It also features a 533 MT/s bus and SSE3, and a 3xx model number (compared to 5xx for Pentium 4s and 7xx for Pentium Ms). The Prescott-256 Celeron D was manufactured for socket 478 as well LGA 775, and they were released carrying model numbers of 355 (3.33 GHz), 350 (3.2 GHz), 345 (3.06 GHz) 340 (2.93 GHz), 335 (2.80 GHz), 330 (2.66 GHz), 325 (2.53 GHz), 320 (2.40 GHz), 315 (2.26 GHz), and 310 (2.13 GHz). They also have hardware-level support of Intel's Intel 64 technology by virtue of it also being built into the Prescott core, although the feature is disabled in all 3x0/3x5 models (with the exception of the Celeron D model 355). It has been activated in all 3x1 and 3x6 models. The Intel Celeron D processor works with the Intel 845 and 865 chipset families. It should be noted that the "D" suffix actually has no official designation although in fact is corresponding to the number "4" as the fourth letter of the alphabet. It is used simply to distinguish this line of Celeron from the previous, lower performing Northwood and Willamette series, and also from the mobile series, the Celeron M.[23] It should also be stated that unlike the Pentium D, the Celeron D is not a dual core processor.
The Celeron D was a major performance improvement over previous Netburst Celerons. A test using a variety of applications, run by Derek Wilson at Anandtech.com, showed that the new Celeron D architecture alone offered up performance improvements on average of >10% over a Northwood Celeron when both CPUs were run at the same bus and clock speed.[24] The addition of SSE 3 instructions and the higher FSB only added to this already impressive gain.
Despite its many improvements, the Prescott core of the Celeron D had at least one major drawback: heat. Unlike the fairly cool running Northwood Celeron, the Prescott-256 had a class-rated TDP of 73 watts, which prompted Intel to include a more intricate copper core/aluminum finned cooler to help handle the additional heat.[25]
In mid-2005, Intel refreshed the Celeron D with Intel 64 and XD Bit (eXecute Disable) enabled. Model numbers increase by 1 over the previous generation (e.g. 330 became 331). This only applied to LGA 775 Celeron Ds. There is no Socket 478 CPU with 64-bit or XD Bit capabilities.
In Intel's "Family/Model/Stepping" scheme, Prescott Celeron Ds and Pentium 4s are family 15, model 3 (up to stepping E0) or 4 (stepping E0 onwards), and their Intel product code is 80546 or 80547, depending on socket type.
