Date:
Sunday , December 28, 2003
Author:
Kyle Bennett
Editor:
Sean Quinn
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Prescott and Upgrading

Very simply put, can you upgrade from Northwood to Prescott on your current mainboard? The simple answer is, some of you will, and some of you won't.

Our Focus:

There has been a lot of speculation in recent months about whether or not the upcoming Intel Prescott CPUs will work with current Intel 848/865/875 chipset based boards. After compiling information from a variety of sources, including the web and some of our insider contacts, we think we have finally gained some real insight into this question that is on a lot of enthusiasts’ minds. Let’s just say there is some good news, some bad news, and some news that will make you wonder just what in the world Intel is doing.

Prescott Rumors:

First let’s cover the Prescott basics that we discovered so far. We will classify most of this as rumor since Intel has not publicly substantiated any of this, but much of what is described below has been verified by many different sources. As it has been publicly discussed by more than a few websites, Intel's new Prescott processor will be making its debut in early February 2004. We will likely see CPUs built on the new 90 nanometer process scaling from the mid-2GHz range utilizing a 533MHz bus to 3.4GHz running on a 800MHz bus, with “Extreme Edition” CPUs rounding out the top of the pack. These CPUs will launch in the current Pentium 4 socket 478 packaging and will carry the Pentium 4 namesake. They will also transition over to a 775-pin package as the speeds climb. While it is currently unclear, most of the CPUs will be HyperThreading compatible though some will not.

As for us enthusiasts, we may find some good reasons to upgrade to Prescott CPUs. While looking over the future offerings, there are a couple of Prescott CPUs that may have a special place with the enthusiast. It seems that some new Prescotts will have a 533MHz (133MHz QuadPumped) bus speed, unlike its 800MHz big brothers. At that bus speed the CPU would have a very high multiplier, possibly in excess of “20”. Because much of the reason the Prescott is being put into production is to give the Pentium 4 line of CPUs some scaling headroom, it’s very likely the parts in question could be great enthusiast CPUs, coming in at less than US$200 at the OEM level. It is unclear if it will benefit from the 1MB of L2 cache like most of the other Prescott CPUs however. In any case, there appears to be a good chance at some great CPUs for the enthusiast at the bottom of Intel's initial Prescott product lineup, should availability be present.

Chipset Rumors:

So, what chipsets will support Prescott CPUs? Many are telling us that Intel's current i865PE and i875P chipsets will support the Prescott Pentium 4 just fine and some have even mentioned i848 support. I’m sure that’s a big relief for many of you out there that have made that purchase in the last year, but don’t break out the party favors just yet because it is not that black and white. There is something everyone needs to understand before they spend any of their hard earned cash on a new CPU with the mindset that it will be a simple upgrade. Just because your chipset supports Prescott does not mean your mainboard will. Yes, you read that correctly. While your chipset may technically support Prescott, your mainboard may not have been built to the correct power standards to support Prescott CPUs.

As for next-gen mainboard chipsets that will support Prescott, it looks as though Intel will "soft launch" their Grantsdale and Alderwood chipsets in April at Cebit in Germany. From what we were able to derive, these two chipsets do not yet have part numbers and have not been final sampled to mainboard builders at the time of this article. It will likely be the second quarter of 2004 before we see any mainboards for sale in the retail channel carrying either of the two aforementioned chipsets. They are basically the same chipset, but the Alderwood will be the premium chipset, just as Canterwood was to the Springdale chipset. Grantsdale and Alderwood will come in discrete and integrated graphics versions. Grantsdale and Alderwood will support DDR II memories up to 533MHz, PCI Express X1 and X16 standards, and next generation LGA775-pin packaged Prescott CPUs.

The Mainboard Question:

Now that we know what CPUs and chipsets are going to be here soon, it certainly raises quite a few questions. The biggest one being, "Am I going to be able to run a Prescott CPU on my current i875P or i865PE mainboard?" And again, as we even spelled out in our article tag line, some of you will and some of you won't. Figuring out which group you’re in is where it really gets a bit tricky.

It all really depends on how "Flexible" your mainboard is. Have you ever heard of FMB specifications? A simple introduction can be found on this AVC OEM HSF page. Did you notice what’s spelled out on the very first line?

Slim PC INTEL P4 Prescott FMB 1.5

Ignoring the "Slim PC" form factor text, we see the "Intel P4 Prescott FMB 1.5" spec noted several times on the linked page regarding the cooling solutions needed for Prescott. There are also Prescott entries on that page that do not contain the "FMB 1.5" qualification. It is our understanding that mostPrescott CPUs will need a FMB 1.5 compatible build specification to operate reliably. FMB or "Flexible Mother Board" specifications have been around for a while, and most current mainboards are built on the FMB 1.0 spec. It is our understanding that the documentation of these specifications is kept confidential. One very reliable source that we have seen openly disclose FMB specifications is AnandTech on this page within a SiS 655TX chipset board review. There is a table that outlines the required current for FMB 1.0, FMB 1.5, and FMB 2.0 specifications. The author says this about the SiS 655TX:

655TX also fully supports FMB (Flexible Motherboard) 2.0 and VRM (Voltage Regulator Module) 10.0 specifications. This means full compatibility with upcoming Prescott processors. Both the Asus and Gigabyte manuals list Socket 478 Prescott processors as fully supported on their 655TX motherboards.

Looking at the chart, you will see the current scale from 78A, to 91A, and finally to 119A with FMB 2.0.

As mentioned above, most Pentium 4 motherboards are currently built on the FMB 1.0 spec, but this does not mean that there are no forward looking companies in the industry. MBReview.com is quoted as saying this on July 14th of this year:

Hey all, I just received word from Platform Development personnel at Gigabyte. It seems that all of their i865 / i875 motherboards that are currently on the market were designed with FMB 2.0 and VRM 10.0 guidelines in mind. As many of you may have already read, the problem that is arising deals with the so-called mandatory FMB specification move from 1.0 to 1.5. Since the Gigabyte motherboards were designed with FMB 2.0 in mind, this would appear to make them fully compatible with both the current Northwood core Pentium 4's, and the upcoming Prescott core processors.

Gigabyte has recently confirmed in writing the validity of the above statement. Notice, however, that the above statement says that the boards meet the “guidelines” and not the “specifications.” Gigabyte is not the only company trying to meet FMB “guidelines” needed by Prescott CPUs.