by Ilya Gavrichenkov
05/20/2009 | 06:13 PM
Our readers often ask: how many computational cores should a contemporary processor have? Unfortunately, we can’t give you one exact answer to this question because the need for a certain number of processor cores is very dependent on the type of tasks each user works with most of the time. Our tests show that quad-core processors are extremely efficient during rendering and video encoding, but most games, office applications or even graphics editing tasks can’t really load all four cores simultaneously. Moreover, there are quite a few applications, which do not split the load into any parallel threads at all. Among them are some sound codecs, several games, Internet browsers and even Adobe Flash Player: they all use only one computational core. Therefore, it may be not a trivial task to find the most optimal processor for your particular usage model, especially taking into account that currently there are solutions with different number of cores within the mainstream price range – one, two and four.
Nevertheless, the most universal choice today would be a dual-core processor. Almost any computer system will be able to load two computational cores with work: even if the active application uses only single-thread algorithms, the second free core will come in handy for the needs of the operating system that will be able to react faster to user actions this way. The statistics is also in favor of dual-core CPUs: almost half of all computer systems today are equipped with dual-core processors. And even though the price drops on CPUs with more computational cores have been forcing the share of these computer systems to get smaller lately, the number of dual-core bases systems is still almost twice as big as the number of quad-core ones out there.
In other words, it is the dual-core CPUs that remain of primary interest to computer users these days. Speaking of the specific product lineups from the leading makers, we have to admit that Intel dual-core processors may seem more attractive. The microprocessor giant is currently offering a considerably larger variety of dual-core solutions in three different price segments: Celeron, Pentium and Core 2 Duo. AMD can only respond with two families: Sempron and Athlon X2 that cannot compete with Core 2 Duo from the consumer functionality standpoint.
So, it makes sense to consider alternative dual-core solutions only in the sub-$80 price range. These particular inexpensive dual-core Athlon X2 and Pentium processors will be most demanded by a pretty significant group of users assembling inexpensive systems priced at $500 maximum. Our today’s review is going to target these users as it is going to talk about the competition between AMD Athlon X2 and Intel Pentium CPU families.
The dual-core AMD CPU lineup has recently been changed dramatically. Namely, AMD has shifted the focus to Athlon X2 7000 series solutions based on Kuma core. As a result, Athlon X2 7750 is not the only solution in the market today: you can also get a faster Athlon X2 7850 working at 2.8GHz frequency. At the same time, they retired a vast majority of Athlon X2 CPUs on Windsor and Brisbane cores. The reasons for these drastic measures are pretty common: it becomes not cost effective to manufacture special cores for inexpensive dual-core processors that is why CPUs based on defective quad-core semiconductor dies become more and more widely spread.
So, the number of dual-core AMD processors on K10 (Stars) microarchitecture that also have a 2MB L3 cache keeps growing. However, it is important to remember that Athlon X2 from the 7000 series is a derivative from the first-generation Phenom X4 CPUs on Agena core manufactured with old 65nm process. It means that Athlon X2 7000 series work only in Socket AM2/AM2+ mainboards and support only DDR2 SDRAM.
You can check out the key specifications of Athlon X2 processors on K10 (Stars) microarchitecture on the screenshot from the diagnostic CPU-Z utility, for example:
There is nothing unexpected here. The top Athlon X2 7850 model turned out only 100MHz faster than the predecessors we had already reviewed before. It works at 2.8GHz clock speed. Everything else remained exactly the same. Therefore, we shouldn’t expect the new Athlon X2 7000 series to work any wonders: their performance is just a little different from that of Athlon X2 on K8 microarchitecture, these CPUs do not overclock too well and have pretty high heat dissipation. However, nevertheless, there is not much choice for us at this point, and those of you who decide to go with a dual-core AMD processor will have to put up with all these drawbacks, at least until the company is ready to offer us new dual-core solutions on more advanced 45nm cores.
Unlike AMD, Intel has long introduced 45nm production process for almost all their CPUs. The only exception here are probably the only budget Celeron processors. As for the Pentium processors that we are primarily interested in today, all members of this CPU family with E5000 model numbers are based on 45nm Wolfdale-2M core that is created from fully-functional Wolfdale core used in Core 2 Duo CPUs by disabling part of its cache-memory.
As a result, dual-core processors that will compete against Athlon X2 family (at least in terms of pricing) feature 2MB of L2 cache memory, which is only one-third of what fully-functional Wolfdale processors have. However, this is far not the only parameter that has become worse when they turned Core 2 Duo into a three times cheaper processor. E5000 Pentium series use slower 800MHz FSB and work at lower clock frequencies than Core 2 Duo.
As a result, the main specifications of Pentium E5400 CPU that tops the E5000 series look as follows on the screenshot from the diagnostic CPU-Z utility:
Speaking of Pentium processor family we would like to stress two peculiarities that most buyers often forget about. First, unlike all other LGA775 45nm Core cores, the CPUs from this model lineup do not support SSE4.1 instructions. I would like to remind you that this set consists of 47 instructions and is used by several contemporary video codecs. However, you shouldn’t be too upset about it, at least since Athlon X2 also doesn’t support these instructions.
The second and more serious drawback of Pentium processors is the absence of virtualization technology support. Although it used not to matter that much for home users before, now things may change to completely the opposite. The thing is that the upcoming Windows 7 operating system will use virtualization technology for Windows XP emulation mode. Since the CPU doesn’t support this technology, it would be impossible to launch a virtual machine with an outdated but yet very widely spread operating system in the new OS.
When we decided to compare the latest dual-core processors priced between $60 and $80, we focused our attention on Athlon X2 7850 and 7750 as well as on Pentium E5000 family. Unfortunately, we don’t have the new Pentium E6300 CPU in our lab yet, so we have to postpone the tests of this model for now. However, we also added the results for the old AMD Athlon X2 6000. Although this processor is based on K8 microarchitecture and is not on the official AMD price list anymore, it still can relive the past and demonstrate sufficient performance for the products within the considered price range. So, here is the complete list of CPUs participating in our today’s test session:
I would like to point out that although we decided to compare Athlon X2 processors against Intel Pentium CPUs, AMD solutions are still a little cheaper. However, we didn’t include dual-core Celeron CPUs into our today’s test session on purpose, because they occupy a much lower place in the processor hierarchy in terms of consumer features as well as price.
To test all the CPUs listed in the table above we put together two similar platforms for Socket AM2 and LGA775 processors respectively. Below is the list of hardware and software components used for them:
Although AMD Athlon X2 7850 and 7750 processors can work with DDR2-1067 memory, we tested them with DDR2-800 SDRAM, just like all the other testing participants. Our decision was mainly determined not that much by the desire to have all CPUs working in identical testing conditions, but mostly by economical reasons. Memory performance doesn’t affect the final system performance score that much that is why most users building a PC on a budget prefer to use more affordable rather than high-frequency memory.
The results of our tested processors in complex performance benchmarks are quite natural. Overall, the CPUs lined up on the diagrams according to their price. The only thing I would like to specifically point out is the advantage of Athlon X2 in Productivity pattern, which indicates that office applications benefit from large cache-memory, and the advantage of CPUs on Core microarchitecture during 3D image creation and editing.
By the way I should also draw your attention to a significant advantage of the new Athlon X2 on Kuma core over the older generation Athlon X2 6000. It illustrates very well the advantage of K10 (Stars) microarchitecture over the previous K8 microarchitecture. However, this advantage is not big enough to make dual-core AMD processors competitive against Intel Core 2 Duo. Unfortunately, in terms of performance, they lose even to the top Pentium models.
The performance in contemporary games is first of all determined by the performance of the graphics accelerator. And as you can see from the obtained results, $60-80 CPUs cope pretty well with the load created by gaming applications and provide acceptable fps rate. It means that Athlon X2 and Pentium processors may suit quite well for inexpensive gaming systems.
However, Pentium processor family is overall a little faster than Athlon X2 7000 series. Strange as it might seem, they lose to the old Athlon X2 6000 released almost two and a half years ago.
Once again we see that DivX codec is better optimized for CPUs on Core microarchitecture. However, the getting more popular x264 codec gives the winners laurels to AMD Athlon X2 processors on K10 microarchitecture.
Final rendering speed in 3ds max is much higher when you have a Pentium based system. Core microarchitecture that allows processing four instructions per clock instead of three seems fitter for heavy computational work.
We can draw the same conclusion when we measure the systems performance during 3D modeling of protein folding process by a famous distributed computing client called Folding@Home.
The performance in a popular Adobe Photoshop graphics editor is also not the strongest side of AMD CPUs. Although Athlon X2 on K10 (Stars) microarchitecture have become faster than their predecessors, it is still not enough to compete successfully against Intel CPUs on Core microarchitecture. However, this is no news for our regular readers: Photoshop, 3ds max and Folding@Home have long been known as tasks that don’t favor AMD processors.
Another application like that is Excel, where Intel processors work almost twice as fast. By the way, Excel is one of those applications where new Athlon X2 7850 and 7750 CPUs also lose to their predecessors on K8 microarchitecture.
The results of WinRAR utility will also be a disappointment for AMD fans. As soon as the CPUs from this maker switched to new microarchitecture, they began to archive slower. So, although AMD Athlon X2 processors used to perform much better than Intel solutions before, now the advantage is really tiny.
Phenom processors manufactured with 65nm process have never been energy-efficient. They looked even less attractive from this standpoint than quad-core Intel processors based on 65nm cores. Now AMD suggests that we should compare the same core of the old Phenom processors in its triple-core implementation against contemporary 45nm Intel CPUs based on dual-core semiconductor dies. I doubt that anything good may come out of it and the outcome of Athlon X2 and Pentium power consumption comparison is evidently predetermined. Nevertheless, we have to check out the numbers in order to estimate the disaster.
The numbers below show the total power consumption of the tested platforms (without the monitor). During our tests we used 64-bit LinX 0.5.8 utility to load the systems to the utmost extent. Moreover, to ensure that we estimate the power consumption in idle mode correctly we activated all power-saving technologies, such as C1E, Cool'n'Quiet and Enhanced Intel SpeedStep.
All processor power-saving technologies get activated in idle mode therefore the power consumption of our test systems doesn’t differ too much. Nevertheless, the advantage of CPUs manufactured using more advanced technological process is evident even in this case.
Things get much worse as the load increases. AMD CPUs can’t compete against Pentium in performance-per-watt – it is for a good reason that these processors are often used in HTPC systems. Athlon X2 on a 65nm core is considerably far behind the Intel offerings, therefore, if you do care about the power consumption and heat dissipation of your system, then forget about dual-core AMD processors for good.
Unfortunately, the Athlon X2’s fiasco in power consumption tests is accompanied by pretty sad overclocking results, too. Of course, the only one to blame is the old 65nm Kuma core that has already proven overclocking-unfriendly before.
This time we checked the overclocking potential of Athlon X2 7000 series trying to achieve maximum clock frequency on a system with the top solution in the lineup – Athlon XP 7850. Overclocking experiments were done on the same platform as the performance tests. We used Scythe Mugen CPU cooler.
However, even with a relatively powerful cooler and processor core voltage increased from 1.3V to 1.475V we couldn’t get the system to work stably at anything past 3.25GHz.
Therefore, the fact that Athlon X2 7850 and 7750 processors belong to the Black Edition series and therefore have an unlocked clock frequency multiplier is a very weak compensation. In reality, these processors can only be overclocked slightly, by no more than 20-25%.
Intel Pentium, however, is a totally different story. These processors are based on 45nm Wolfdale core that is currently one of the most overclocking friendly choices. As a result, by raising the core voltage from 1.25V to 1.45V we could easily push the Pentium E5400 frequency to 4.0GHz with Scythe Mugen CPU cooler.
I would like to stress that not very high USB frequency supported by Pentium processors in the nominal mode helps the overclocking success. Since dual-core Intel CPUs have a locked clock multiplier, we can only play around with the FSB frequency during overclocking. But even in our case when the frequency of our overclocked processor increased by almost 50%, the FSB speed only reached 297MHz. I am sure that any mainboard can do it, even inexpensive platforms on cut-down chipsets like Intel P43, for instance.
So, Pentium overclocking is just as easy as Athlon X2 Black Edition overclocking. However, the results are much more impressive in the former case: against Pentium’s background we can barely consider Athlon X2 as an option for computer enthusiasts.
While performance tests may raise some questions about the most optimal dual-core CPU choice in the ~$70 price range, then power consumption measurements and overclocking tests eliminate all doubts about the answer to this question. Sadly we have to admit that today’s AMD dual-core solutions cannot compete against Intel Pentium CPUs yielding to them from almost all standpoints, except, maybe, pure performance.
But even if we focus only on performance numbers and disregard everything else, the final verdict will hardly change. Athlon X2 7000 series processors yield quite a lot to competitors in many applications, and there are very few tasks where they are better than Pentium E5000. Therefore, there is only one way the today’s dual-core AMD solutions may be of interest to you: if you are looking to upgrade your old Socket AM2 platform. It seems totally unreasonable to assemble a new computer system based on Athlon X2, even if it is a new one of K10 (Stars) microarchitecture.
In other words, the answer to the question we raised in the beginning of our article is totally unambiguous: Intel currently offers better dual-core processors, even if they belong to the Pentium series that has discredited itself during the NetBurst microarchitecture era. Today’s Pentium processors have nothing in common with the old Pentium 4 or Pentium D CPUs, they are based on the same microarchitecture as Core 2 Duo but have an L2 cache of different size, different bus frequency and different clock speed. As a result, the contemporary Pentium series looks pretty attractive offering appealing combination of price, performance and power consumption levels. Besides, Pentium processors are an excellent field for overclocking experiments.
However, we wouldn’t stop our discussion of dual-core processors just yet. The thing is that in about two weeks we are going to welcome totally new dual-core AMD solutions that will be built on the latest cores manufactured with 45nm process. And these CPUs currently known as Callisto and Regor should be positioned as competitors to more expensive Intel solutions than Pentium. We hope that they do much better against their competitors. At least, we have every reason to believe this is going to be true: these upcoming processors will not just get new cores made with more advanced technological process, but will also work at higher clock speeds, feature more cache-memory and support DDR3 SDRAM.