Before reading this article, be sure to read our first Desktop Pentium M investigation, as we will not be revisiting any of the discoveries/conclusions in that article.

At this year's Spring IDF, Derek Wilson, Johan De Gelas and I all sat across the table from Intel's Justin Rattner and asked him a question that had been on our minds ever since Prescott's introduction.  The question went something like this:

Recently, Intel has shifted their focus away from ramping clock speed to increasing performance through other means such as exploiting TLP (Thread Level Parallelism).  Given that Intel's direction today seems to be in sharp contrast to the direction of the NetBurst architecture and especially the direction of Prescott, were the past five years of microarchitecture improvements and innovations essentially a waste? 

Rattner's exact answer encompassed a few items, but the main points were as follows:

1) At the time of Prescott's inception, clock speed is what sold, so clock speed was obviously the top priority; and they did quite well at that.

2) The past few years weren't a waste; after all, research continued in the direction of the Pentium M while all of the work on Prescott and Tejas were being done.

The second statement was particularly interesting because it was the first time that we received something tangible from Intel in regards to this question.  Clearly, significant elements of future Intel desktop processors will be derived from the Pentium M architecture, but as we saw in our first desktop Pentium M investigation, the time for the Pentium M on the desktop isn't now. 

As a mobile architecture, the Pentium M can't be beat.  That statement alone is something many assumed that we were contradicting in our desktop Pentium M article, but the purpose of that article was to look at desktop Pentium M performance, where we determined that it fell behind.  In the mobile world, without significant engineering investment, it is doubtful that the Pentium M will meet its match anytime soon. 

On the desktop, we discovered that there were a handful of limitations to the Pentium M's success:

1) 855GME chipset with only a single-channel DDR333 memory controller
2) Expensive motherboards and high total cost of ownership
3) Low floating point/SSE performance
4) Severely motherboard-limited overclocking

The combination of the four items above meant a few things.  While the Pentium M was an excellent contender in general use applications, its total cost of ownership was significantly higher than an Athlon 64 that performed similarly.  In other applications, the Pentium M simply fell behind the competition for architectural reasons. In those cases, its high price didn't help it out at all either.  The saving grace in many cases required overclocking, but the desktop Pentium M motherboards were far from overclocking monsters for those who were interested. 

In the end, our stance on the Pentium M as a desktop solution was that it's more of a wait-and-see proposition.  If motherboard manufacturers could produce cheaper, better equipped motherboards and if those elements improved performance, then the Pentium M would be worth another look as a desktop alternative. 

We hadn't expected such a solution to come around this soon however, but it has, and not in the form that we originally thought it would.  Both AOpen and DFI have indicated that they were working on updated motherboards based on the mobile 915 chipset, but that they were still months away.  So when we received word that ASUS had a solution to the Pentium M desktop problem, we were caught off-guard.  And rightfully so, as their solution is far from just a new chipset...

ASUS CT-479: Socket-478 to Socket-479 Adapter


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  • Houdani - Thursday, March 24, 2005 - link

    With updates to floating point calculations and adding another core, Intel will need to think long and hard about putting their desktop chips into premature end-of-life in favor of going forward with the PM as their base product.

    Or, to summarize:

    Blah blah blah nothing new that hasn't already been said before blah blah blather.
  • mlittl3 - Thursday, March 24, 2005 - link


    You completely missed the point of the excellent data you obtained. Of course, this is just my point of view but here is my take on things.

    The Pentium III stopped at 1.4 GHz. The Pentium picked up at 1.5 GHz (not including the low and ultra low voltage versions). We all know that the Pentium M is much more similar to the Pentium III than the Pentium IV. What if Intel never created the Pentium IV and continued improvements with the Pentium III? We would have had the Pentium M three to four years ago.

    Intel screwed us all with its monopoly powers and sold high clock speeds to the masses with no thought about the performance of the Pentium IV. The last four years have shown us just that but no one complains or holds Intel accountable. As you have pointed out numerous times, the capital processor of the Pentium IV series, the Pentium IV EE is a complete waste of money.

    In almost all of your benchmarks, the Pentium M shows almost the EXACT same performance as an Athlon 64 clock for clock. I say again, what if the Pentium M was developed at the time the Pentium III was discontinued? Intel and AMD would have matched clock speeds and we would have a Pentium M around 2.6 GHz right now with the similar performance of the Athlon 64 FX-55. The improvements you mentioned in the conclusion for Yonah (SSE and floating point) would probably already be implemented.

    The Pentium M is THE processor from Intel. We had to wait four years for Intel's monopoly to be weakened but now we have a processor worth something. With multiple cores (each running at the speed of single cores since the Pentium M runs so cool) and all the other improvements from Yonah, that processor is going to be awesome.

    Thank god for AMD challenging Intel with their terrific Athlon 64 architecture. Without them, computer processing would be in the dark ages. Guys, we need to stop supporting companies when they get to a certain size. The market needs to shift or we are going to get software like Windows and processors like the Pentium IV. With an even market share split between at least two companies, technology will excel past our wildest imaginations.

    Okay, I will shut up now. I do want to add one thing. The ASUS adapter does nothing over the Aopen motherboard. If I am not mistaken, you compared a 533 MHz FSB, 133 MHz faster Dothan Pentium M to 400 MHz FSB, slower Dothans (I hope the other processors were Dothans and not Banias). The performance delta between the 770 and the 750 is exactly what you would expect from a faster clocked processor and a faster FSB. The 865 vs. the 855GME had nothing to do with the performance difference. The only advantage of the ASUS adapter is a cheaper overall cost of ownership.
  • bob661 - Thursday, March 24, 2005 - link

    Oh yeah, if you're going Intel, this is the only CPU to own. Reply
  • bob661 - Thursday, March 24, 2005 - link

    Intel really needs to lower the price of this CPU. A 765 is $645 on newegg. I can only imagine what the 770 would cost. If it was more price competitve, the P-M would be an excellent processor choice. Reply
  • rqle - Thursday, March 24, 2005 - link

    i thought it did pretty well clock for clock on majority of the benchmark against the amd64 and did on par or so on gaming against the amd FX chips. Where it exceeds the PM it deal extremely well, and falls really shorts on things it didnt fair to well.

    Price wise for a "Desktop", i still believe AMD64 chip is the way to go. Great notebook chip that is not quite ready for the desktop area yet, need to improve its floating point performance and some desktop area. Did pretty well as gaming chip.
  • clarkey01 - Thursday, March 24, 2005 - link

    I mean, your going to get Intel fanboys saying " Its only has a 400 MHZ FSB" and what not. Well, why has it > ? its like saying the FX only has one meg cache, why doesnt it have two ?
  • clarkey01 - Thursday, March 24, 2005 - link

    Mixed bag or what. Reply
  • Aileur - Thursday, March 24, 2005 - link

    All in all seems like a middle of the pack solution. I thought the dual channel would give it a more significant boost but the pentium m seems to stay in the middle of the pack most of the time.
    I would still get it before i ever touched a prescott with a ten foot pole (and im an ex northwood user) but for the price theyre asking for dothans I dont see it being the desktop chip killer i was expecting.

    I wonder though how Intel could clock this thing if it didnt have low power/heat in mind.

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