Although there were a rather astounding number of Pentium 4 models, in practice there was not as much variety as we may think. The Desktop versions of Pentium 4 had three major developments, which can be found in their socket, while those intended for Laptops have known only one format.
As seen in the previous chapter, the Pentium 4s were first released in Socket 423 format, which in practice included a PCB with socket connection pins, on which a much smaller chip was soldered (through BGA balls). This one includes a metal casing, called IHS ("Integrated Heat Spreader"), which previously only existed on the latest Tualatin core Pentium IIIs, and which not only protects the core from the mechanical aggressions of the radiator, but also allows to better distribute the heat dissipation on the radiator. This package kept the same pin spacing as its predecessors (Pentium & Pentium III), with a 2.54mm pitch, which ultimately gave it a fairly large size. A closer look at it, one would rather have said a draft processor, a prototype of what should have been the Pentium 4 from the start, that is to say a processor with smaller legs, less spaced, as in Socket 478.
This format was used for Willamette cores between 1.4GHz and 2GHz, then quickly abandoned in favor of the PGA-478, for the Socket 478.
The legs are much smaller than those of the processors of the previous generations, with a pitch between legs divided by two, of only 1.27mm ! This made possible to greatly reduce the size of the processor, with almost equivalent number of pins compared to Socket 423. Hence the name of µPGA instead of PGA. This format is very similar to the one introduced for the latest Pentium III and Celeron Mobile, certainly for reasons of space, reduction of costs (manufacture requiring less assembly operations), but also technical on the occasion of the abandonment of the platform supporting Rambus RD-RAM. This µPGA-478 format is also looking very close to the small chip soldered on the PCB of the Pentium 4 Socket 423 and uses a similar metal cover.
The first models kept the Willamette core of the Pentium 4 Socket 423, with same frequencies, between 1.4 and 2GHz (one cpu for each increment of 100MHz).
Then they quickly moved to the Northwood core which started at 1.6GHz and ended at 3.4GHz. ! In order to distinguish the Willamettes from the Northwoods of the same frequency, the latter were called Pentium 4A. The "A" was then often added after the frequency for models between 1.6 & 2GHz, where there was ambiguity.
There are only 4 models in this case at 1.6, 1.8 & 2GHz.
When the Northwoods switched to an FSB of 4x133MHz - 533MHz (against 400MHz for the former), they were called Pentium 4B to distinguish them from the FSB400 models of same frequency like 2.4GHz or 2.8GHz models.
A bit like what Intel did during the Pentium III era, with versions B, E & EB.
Then in the same way, the Northwoods with a FSB at 4x200 - 800MHz were called Pentium 4C, again not to confuse them with the others, because they were much superior from a performance point of view. At least, when you knew you were not confused, but when you didn't it was very confusing to see all that similar models with sometimes A, sometimes B or C letters added to the name, sometimes even not, making difficult to know what you could buy.
But then, it became even worst, mouch more complicated with the generation of Pentium 4 Prescott core.
Basically, here again Intel added a letter to them so as not to mix them with the others. But already, while it should have been "D", it will eventually be "E", perhaps so as not to confuse them with future Pentium D they had already in their lab.
But the letter E would only be used for Pentium 4 Prescott with FSB of 800, because those with FSB of 533 would reuse the letter "A" ...
It was complicated but there was no possible ambiguity, because there was no Pentium 4A Northwood and 4A Prescott processor of the same frequency (Intel checked it well. ..).
Obviously, these letters A, B, C & E are almost never indicated on the processors (unlike the Pentium III), causing a certain vagueness, surely voluntary, on what is what
Finally, socket 478 inaugurated also the first processors badged "Extreme Edition" or "EE", based on the Gallatin core of Xeons of the same Netburst architecture. Only 3 models have been released.
At the end of their life, the Pentium 4s ended up switching to another type of format, innovative for the general public at the time, the LGA format.
Farewell bent legs of processors, pins being carried directly by the socket of the motherboard. Actually, by doing that, Intel put the problem further, but for Intel, it was better, and for all, probably too, the socket being much less exposed than a processor.
The pitch between the pads being the same as for the PGA-478 format, the processor slightly increased in size.
There were some Northwoods on this format, some Extreme Edition Galatin, but mostly Prescott and Pentium D.
No mobile version either, the socket being too big for that. Actually, neither Intel nor any other manufacturer have never released a processor in the LGA format for laptops.
It was also on the occasion of this change of format that the numbering of the processors was introduced, because the only indication of frequency was not anymore in favor of Intel compared to AMD , which had already gone to an "equivalent frequency" indication since the Athlon XP, similar to what Cyrix did for its 6x86 (and MII).
This numbering system was used only for the LGA-775 Prescott & Pentium D and was so complex that I must dedicate a full chapter to describe it.
We will not go deeper into the reasons that made Intel to switch to this now generalized numbering system here, but let's have a look into the logic behind the numbers to decode the meaning of a processor number.
- The first digit starts with 5 for Pentium 4 without the SpeedStep function, with 6 for Pentium 4 with.
- The last two digits allow to differenciate the frequencies. Higher they are, higher the frequency is and therefore more powerful the processor is (since they are all based on the same core). Basically, the last two digits change from 5 to 5 for models with an FSB of 533MHz, then from 10 to 10 for those with an FSB of 800MHz.
It starts from x05 for a frequency of 2.66GHz and goes up to x70 for a frequency of 3,8GHz. Models with a number less than x20 have a 533MHz FSB, and normally, with the exception that we will see below, those with a number greater than or equal to x20 have a 800MHz FSB.
- The letter "J" at the end of the processor number defines models with Execute Disable Bit capability.
From this, let's say it's pretty simple. But models with numbers ending with 1 and 6 also emerged later.
On 5xx models, these numbers are used to distinguish the models with EM64T (so 64-bit) from the same models without, with an processor number ending with 5 or 0 (example: 510 & 511 or 515 & 516).
But on 6xx models, the ending "1"is used to identify models with Cedar Mill core, 0.065µm (against 0.09µm for the other models, allowing them to have a lower TDP) ! And they all have EM64T.
There is no 6x6 models because there is no 6xx with 533MHz FSB, for those who follow.
Note that the models with a processor number ending with 1 or 6 also have the Execute Disable Bit capability, even if they do not have a "J" at the end.
But that's not all. There are plenty of exceptions in "small" processor number models :
- a 517, which is actually a 516 with Hyperthtreading function
- a 519, a 519J and 519K: These are models with a FSB 533MHz, like 515/516/517, and with a frequency incremented of 133MHz from them, so running @3.16GHz.
Main reason is surely, because Intel could not use the 520, as it was already taken for a FSB800 model previously released and, it's a pity, running at a lower frequency than the 515, 516, 517 & 519 ...
And the height of the roof, Intel also released a 524, which actually is a 519 with Hyperthreading, that Intel could not neither call 520 ...
Finally there are two models with a processor number ending with 2 : 662 & 672, which are same than 660 & 670 but with Virtualization.
In short, processor numbering from Intel, it's a bit like French language : it came from a good intention with simple rules and then deviated with a lot of exceptions, making the whole a little confusing...
And this was also an opportunity to multiply the number of models in the catalog, since there are 42 Prescott LGA775, which is more than Pentium 4 Socket 478 all cores combined (Willamette, Northwood and Prescott) !
Did I loose you with the Pentium 4 numbering system ? If not, let's continue with the Pentium D, which are Pentium 4 Dual Core, available only in LGA-775.
The Smithfield core models (0.09µm) are numbered 8xx, with a slower model 805 with FSB533, and 8x0 models with FSB800.
There is also a Pentium Extreme Edition 840 running at the same frequency than the Pentium D 840, but with Hyperthreading.
Then there are the models core Presler, 0.065µm, with numbers ending by 5 (between 915 and 965), although there is no model FSB533.
Another exception, the 9x5 the models do not have the virtualization while 9x0 have.
All Extreme Edition models have Hyperthreading (but not the Intel SpeedStep feature that all other 9xxs have).
Compared to the Pentium IIIs, the mobile Pentium 4 line has been greatly rationalized in terms of packaging. No package diversity here, from beginning to end, the Pentium 4 Mobile used PGA-478, the same as that of the desktop version. On the other hand, some models have an IHS like desktop models and some others not.
Mobile versions have only used Northwood and Prescott core with 400 or 533MHz FSB only. So, no Pentium 4A or Pentium 4C as with Desktop. Just Mobile Pentium 4 "full stop" for FSB400 versions of Pentiums 4B Mobile, even when, for FSB533 versions.
The Pentium 4 with FSB400 have no IHS, except the 2.3GHz version. All Pentium 4B models have all an IHS.
The Prescott core models uses processor numbering system. Except one, of course, it would be too easy otherwise. There is indeed a Mobile Pentium 4 2.8GHz Prescott, without number.
As there is no Mobile 2.8GHz Northwood Pentium 4 with FSB 400MHz, this number-less Prescott is simply named Pentium 4 Mobile 2.8GHz and the Northwood Pentium Mobile 2.8GHz, 4B.
Some (3) Northwood models exist , at equivalent frequency, with or without Hyperthreading. Whithout any numbering system, where appropriate, thoses Northwoods have "with HTT" (HTT = Hyper Threading Technology) added at the end of their name.
Regarding the Prescott models : they all have IHS, and like Desktop ones, Hyperthreading. They also all have same functionalities and are all using a 533MHz FSB.
The numbering of mobile Pentium 4 Prescott, thereby, it is much simpler than desktop models :
- they all start with 5xx
- the last two digits are incremented as the frequency increases, but without any real logic:
Numbers start from 518 for 2.8GHz, then 532 for 3.066GHz (so with an increment of + 266MHz), then 538 for 3.2GHz (increment of 133MHz), then 548 for 3.33GHz (again an increment of 133MHz) and finally 552 for 3.46GHz (133MHz increment also) ...