Intel Pentium 4 641 (Cedar Mill) - 65-nm process technology advancing

Introduction

Keeping the computer "at the cutting edge of progress" is a very hard and definitely not cheap thing, especially in our rapidly developing world. No sooner had the situation with graphic adapters stabilized than new cataclysms came up, which resulted in global changes on the processor front. The announcement of new AMD AM2 platform has not indeed made serious trouble, it hasn't brought anything radical to the world, but quite little time has left before the official announcement of Intel Conroe. That is why most people are not hasty at buying a new processor - everybody is in the hiding and waiting. This calm before the storm is urged especially by regular news of the latest Conroe tests and that AMD is in for a trouble. In this situation, AMD representatives keep calm and cool and are not showing any signs of apprehension.

The outcome of this intrigue will come soon, but for now in the calm period new single-core Intel processors came in quietly to the Russian market which are supposed to be a replacement for the "oldies" based on the Prescott core. I mean the processors built on the Cedar Mill core. This core is not new - we've known it for a long time and we came across that in dual-core Intel Pentium D processors. The Cedar Mill core is half the Presler core which is produced following the 0.065-mk process technology and underlies the dual-core Intel Pentium D series 9õ0 processors. In other words, I mean single-core Intel processors created following the 0.065 mk process technology.

Although Conroe is not far off already, in will arrive in Russia in no less than 2 months; besides, we are definitely in for sheer profiteering with "hot" novelties. But what if we need a new processor right now? After the drop of prices in April, Intel's dual-core processors have turned just a little bit more expensive than single-core, but for now it is hard to see the advantages of dual-core processors, and a processor like that requires a powerful PSU and good cooling. But there is another side of the coin - when overclocking Presler processors it is a rare occasion to get over the 4 GHz bar, and in so doing a very high heat emission has to be cooled. What if we remove one core out of the Presler? Of course, the frequency potentials of the processor should be much higher and the heat emission quite moderate. This is just the way the single-core Intel Pentium 4 (Cedar Mill) appears to be.

In fact, the Cedar Mill core was announced quite a long time ago, but for unknown reasons processors on its base have appeared in the Russian retail quite recently. Somehow or other, we are getting familiarized with them closer today.

The 0.065 mk process technology and a single core

We should point out the following straight off: The new core Cedar Mill does not offer improved performance as compared to the customary Prescott 2M, but on the other hand, the new "fine" process technology gives certain hopes for reduced power consumption and heat emission.

So, we have clarified that Cedar Mill is merely a half of the dual-core Presler, is produced following the 0.065 mk process technology like the Prescott 2M core, offers 2 MB of L2 cache size, and the 800 MHz system bus. Basically, all the specifications of Prescott 2M can be extended to Cedar Mill as well. As is usual, the marking has been incremented by one digit: Intel Pentium 4 630 -> Intel Pentium 4 631. It is just the "1" at the end of the name that points to the 0.065 mk Cedar Mill core. Intel have repeatedly mentioned processors whose name ends with «3» which will offer support for the Vanderpool Technology; the company even sent out specimens of these processors for tests, but currently they can't be made available either on sale or in Intel's product lists. Our search of information on this subject has brought interesting results: there have been found only 2 processors with support for the Vanderpool Technology, and their marking ends with "2" but not "3". Besides, these processors have not yet been fully sent to the retail - only a few shops offer them in their price lists, so we can't yet judge about their prices.

We suggest that you look at the table of processors whose existence and availability in the retail is authentic.

As you can see, Intel Pentium 4 (Cedar Mill) processors are available for sale in Moscow at clock speeds up to 3.6 GHz. Pentium 4 662 and 672 offer support for the Vanderpool Technology (VT), but they haven't yet appeared on the market, especially Russian.

Haven't the latter two processors in this table attracted your attention? Who would doubt of that? These are nothing more than Intel Celeron created following the 65-nm process technology. But the most important thing which catches the eye is the doubled cache memory size - it now amounts to 512 K. No doubt, that will essentially improve their performance.

Evidently, Intel has done something to Celeron which is different from Pentium 4, and the new core Cedar Mill-V is used only in top-end processors of the Intel Celeron product line. There is also information on the third Celeron processor built on the Cedar Mill-V core which will be marked as Intel Celeron 360 and run at 3.46 GHz, but its release is planned for the middle of the summer.

Now let's explain one more most interesting point. Which chipsets support processors built on the Cedar Mill(-V) core? It is hard to answer this question clearly, so the thing is not about the chipset. It is most likely about the motherboard. To make a motherboard support Cedar Mill processors, the power scheme should conform to the VRM 10 standard. This is the standard all the boards aimed at Intel dual-core processors (chipsets i945, i955, i965, i975) conform to.

To avoid mishmash in the matters of support, Intel has introduced a special scheme of marking that points to the compatibility of platforms. It is called the «Platform Compatibility Guide» (PCG) and is designated on the processor's box and should also be shown in the specification of the motherboard.

On the processor's box, this mark can be found on the front sticker, under the hologram:

Below, under the «Platform Compatibility Guide» label there is the marking «05À» which is just the factor of platform support. In the motherboard's specification, this factor is normally shown in the "Supported processors" section. For example, here are the extracts from the Instructions on ASUS P5LD2 (i945P) motherboard:

P5LD2 specification summary

The required line is highlighted in the bold type. If this line shows only «PCG 04B/04A», then your motherboard can's support processors built on the Cedar Mill core. Unfortunately, not all manufacturers find it necessary to show the factor of platform compatibility - for example, we couldn't find this mark on Gigabyte's and Foxconn's motherboards. There is one thing we can state with confidence – all motherboards with support for Intel dual-core processors fall within the PCG 05B/05A category, so we can use that as a guideline.

We can also add that most motherboards built on the nForce 4 SLI Intel Edition chipset which also support dual-core Intel processors conform to the PCG 05B/05A compatibility factor.

If your motherboard (conforming to PCG 05B/05A) is not yet able detecting the new Cedar Mill core, simply update the BIOS with the most recent version.

Intel Pentium 4 641

We received an Intel Pentium 4 641 processor in our test lab for evaluation; this model runs at 3200 MHz (200õ16) and offers 2 MB cache, so we'll be comparing it versus the younger brother Intel Pentium 4 640 based on the "good old" Prescott 2M.

Of course, new processors are packaged into boxes with the modified «Intel» logo.

The inscription «Intel EM64T» on the box has been removed because this technology is already supported by all Intel processors, so it makes no sense reminding of that.

The interior of the repainted box has remained the same: the processor and its cooler are packaged in a plastic corset. The cooler has a copper core, which is definitely nice.

It seems like Intel is anyway trying to take care of the acoustic properties of its products – despite the reduced heat emission of the new processor, it is equipped with an effective cooler, which means it won't have to wound up to the full, torturing the ears of the users.

There aren't any changes on the heat-spreading lid - the differences are only in the marking, but the changes on the "belly" of the processor are seen even to the naked eye.

For Intel Pentium 641, a greater number of finer external components has been used. Don't mind the color of the textolyte - this difference is most likely related to the origin of processors: the Intel Pentium 640 arrived to us from China, and Intel Pentium 641 from Malaysia.

We proceeded with further examination of the processors with information utilities. This is what can be found out about the Intel Pentium 4 640 with the known utility Everest 2006:

The processor has the Prescott 2M core of revision N0, supply voltage 1.3 V and falls within the typical 84W heat package.

This is what the programs tells about Intel Pentium 4 641:

This is Intel Pentium 4 641 based on the Cedar Mill core of earlier revision Â1 - surprisingly, its multiplier's minimum value is 12 and not 14 like in Prescott 2M, which means the processor is able reducing the clock speed to 2400 MHz in the power-saving mode.

The chip area has gone down substantially: from 135 mm2 in Prescott 2M to 81 mm2 in Cedar Mill. The supply voltage has also slightly gone down – 1.275 V versus 1.3 V in Prescott 2M. All these changes are supposed to reduce the heat emission and provide a higher clock speed.

Despite the reduced minimum multiplier, the EIST (Enhanced Intel SpeedStep Technology) wouldn't work at all like other concomitant power-saving technologies - Enhanced HALT State, and Thermal Monitor 2. This is explained by the earliest revision «Â1» in which support for these technologies was not brought to perfection. The next revision «C1» has already been released and soon will be available to us. Recently, Intel has been increasingly "playing tricks" with releasing processors with "raw" revisions, but let's hope this is a temporary problem caused by the war against AMD. By the way, revision «Ñ1» promises to bring not only support for power-saving technologies but also an improved clock speed margin.

Everest 2006 did not display information on the typical heat package, but using other utilities we were able to find out that the processor fits within the 86W heat package. At first glance, it is a bit surprising that the "colder" processor offers the TDP greater by 2 W, but it turned out that all Intel Pentium 4 (Cedar Mill) processors up to 3600 MHz (Intel Pentium 4 661) fit within this heat package.

Benchmarking

Despite the theoretically equal speed, we anyway decided to run a series of tests to clarify all the doubts on this matter. As benchmarking suites, we used both synthetic benchmarks and real applications: games and other. Their list looks like this:

• 3DMark’03 v.3.6.0
• 3DMark’06 v.1.0.2
• PCMark’05 (v.1.1.0) CPU test
• SuperPI (8M)
• SiSoftware Sandra 2007
• WinRAR 3.60 (beta3)
• FEAR
• Quake4

To test the processor, we assembled a test bench which would be able demonstrating all the overclocking capability of the processors because migration to a finer process technology promises a lot of surprises for the overclocking fanciers.

The first thing to do, we'll verify the performance of the whole system in famous gaming benchmarks by Futuremark.

There was a good reason to choose 3DMark’03 and ’06 - 3DMark’03 is highly responsive to the change in the system performance, whereas 3DMark’06 is sort of a new performance standard. As is seen on the graphs, however sensitive these benchmarks are to the system performance, the results for both processors are almost equal.

The task of the second stage is more specific - to run the CPU test in 3DMark:

Again, the results are almost identical.

We again turn to Futuremark benchmarking suites, this time to the famous PCMark’05.

The difference in results is most likely caused by the errors, but with a bias towards the Cedar Mill. We are going further and trying to calculate the "PI" number with SuperPI at 8 mln digits precision - the fewer seconds it takes for the processor, the better result is:

Again we see a parity. Trying another most popular synthetic benchmarking suite - SiSoftware Sandra 2007 - which offers very convenient arithmetic and multimedia CPU tests. The produced results have proved expectedly familiar:

All is the same - just minor chaotic discrepancies. At the final stage, we run a few tests in real applications. For instance, archiving - a typical task for the computer:

Let's not forget that computer games are known to be the most popular among "demanding" tasks for the home computer.

Whistle! Both rivals are at the pedestal, and we have to admit that friendship has won. In fact, we knew that from the very start. The Cedar Mill core was not supposed to bring any changes to the performance but merely to raise the bar of maximum operating frequencies and improve the heat characteristics of Intel Pentium 4 processors.

First, let's talk about the heat characteristics. Of course, we were mostly interested in finding out about the heat emission of both the processors, but after producing absurd results we had to run the tests repeatedly and look for the cause. The cause proved so banal and sad that you lose heart. Formerly, when testing coolers we mentioned that the non-uniformity of the heat-spreading lid of the processor may spoil the whole cooling process from scratch, so whatever cooler you fit on a faulty processor - that will be of little use.

This time, the situation turned out to be similar. To verify the uniformity of the base, we used the simplest "old-world" method: a superfine layer of thermo paste is applied on the glass surface so that it is translucent, and then the processor being tested is placed with its "belly" up and pressed from the top. In the end, on the heat-spreading lid of the processor there remain distinct traces in the points of contact with the smooth glass surface.

Look what has been produced based on the totals of verification for Pentium 4 640 and 641 under study:

The lid of Intel Pentium 640 is arched over the center, and in Intel Pentium 641 it is concave over the center. Remember that just under the central part of the lid there is the processor core, that is, this part is the "hottest" point and the most important is the maximum contact with the cooling system. Hence, Intel Pentium 640 and Intel Pentium 641 are in equal conditions, so it is hard to compare their heat characteristics in such conditions.

Search for information in the Internet allowed us to make a conclusion that the power consumption of the processor on the new "finer" Cedar Mill core has gone down by approximately 20% versus Prescott 2M. Therefore, the heat emission should go down accordingly.

Once there is no way to compare heat emission of processors, there is a proven method to verify the «dividends» of the new process technology – the clock speed increase margin should increase essentially, and overclocking may reveal that. Now it's now time to move from tests on to overclocking.

Overclocking

While describing the test bench, we hinted that its configuration had been specially selected in view of overclocking features, so we came across no obstacles for overclocking. The key role of the processor cooler was played by the known GlacialTech Igloo 5700MC cooler which has repeatedly shown itself as a leader among processor coolers, and the housing ThermalTake Xaser III provided superb ventilation of the whole system.

First, we started squeezing the most of the "old guardian" Intel Pentium 640. We have to admit we received quite a successful processor specimen: without raising voltage, it easily overclocked to 3900 MHz, and on raising voltage to 1.55 V we were able to achieve a stable operation at 4200 MHz. We can state that 4200 MHz is rather standard overclocking for the Prescott core in the conditions of good cooling.

We got round to overclocking Intel Pentium 641 with enthusiasm and expected some "miracle", and fortunately our expectations came true. We first wanted to overclock the processor without raising voltage starting from the 3900 MHz bar, but we dared for 4200 MHz from the start. Imagine how surprised we were to see that Intel Pentium 641 at this clock speed was able to boot up the system and ran all the stability tests without a problem. On further raise of frequency we came across errors in the tests, so we had to acknowledge 4200 MHz as the maximum stable clock speed.

The new Cedar Mill core allows to overclock the processor without raising voltage to frequencies which were formerly possible to attain only through raising voltage and with good cooling. An impressive result!

But the potential is not yet exhausted, so we moved on to raising voltage on the processor to 1.55V. In view of not the most successful topology of the heat-spreading lid, the mode of cooling the processor proved quite poor, which is especially seen upon raising voltage - the temperature was going up sharply.

Nevertheless, we were able to boot up easily and make the system run stably at the fantastic clock speed 4700 MHz, and on further minor raise in voltage we even were able to start up the system at 4800 MHz!

Unfortunately, we failed to verify the operational stability of the system at this clock speed – the sharp rise of temperature upon starting the test did not make it possible to run the test to the end, but we can state with confidence that for our processor specimen the maximum stable clock speed on raising voltage to 1.55 V is within 4700…4800 MHz, which is indeed impressive, isn't it?

You can imagine the shining eyes of overclockers, but this joy had to be overshadowed because to attain such high results you have to have a motherboard which is able raising the frequency of the clock generator from 200 MHz to 320-330 MHz. It is important not only to raise voltage and clock speed but to operate stably at these frequencies because in so doing the FSB speed exceeds 1200...1300 MHz. Far not every motherboard can afford that. Just a piece of advice to beginner overclockers: to get over higher FSB speeds, it is a good idea to slightly raise voltage on the North Bridge and take care of its proper cooling.

Conclusion

Summing up the results of tests, we can state with confidence that Pentium 4 641 (Cedar Mill) has indeed proved successful. But its "hobby-horse" is not in the performance but the superb overclocking capability.

If you intend to use the processor in the nominal mode, then the most promising choice for you would be to buy its dual-core brother which is priced 25$ higher.

If you plan overclocking, the situation is changing. The overclocking capability of a single-core processor on the Cedar Mill core is much higher than that for the dual-core Presler. Modern applications have not yet migrated to computational multithreading, which means that higher clock speed would be of better use than two cores. Such situation will remain for quite a long time. In this regard, it turns out that the single-core Cedar Mill processor may prove a more advantageous choice rather than its dual-core analog. Besides, we have already mentioned that the single-core Cedar Mill offers much smaller power consumption and heat emission. At the same time, soon we will see processors of renewed revision «Ñ1» which will add the promised power-saving technologies and let achieve clock speeds as high as 5 GHz!

We'd better forget about Prescott processors - the only thing what may make them attractive is their very low price. This is most likely to happen soon - already now only their old stocks are selling. This is especially topical in view of the forthcoming release of the new Conroe core, which should make the prices for single-core processors go down by 8% to 54%.

As regards the "Cedar Mill versus Conroe" comparison, Intel has run passions so high that their new processor core is depicted as "devil out of the box". Let's not run into panic until we are able to verify the capabilities of Conroe in our test lab. Time will come, and we'll definitely conduct a comparison of performance of all these processors in action, but for now we confirm the following final conclusion. If you are up to overclocking the processor, your current choice would be a single-core Cedar Mill, if you are against such a "torture", then you can pay extra 10 $ - 30 $ and better get a dual-core processor built on the Presler core.

We appreciate the computer megamarket chain Unicom for the presented and tested hardware.