Intel Core 2 Duo Threatened: AMD Phenom II X3 720 Black Edition CPU Review

AMD have started to use new 45nm core for their unique triple-core CPUs. As a result, there appeared a very attractive solution for the mainstream segment. And taking into consideration remarkable potential of the Phenom II X3 CPUs, we have every reason to conclude that it is going to be a new sales hit.

by Ilya Gavrichenkov
03/20/2009 | 01:54 PM

The launch of the new Phenom II processors that are built using the latest 45nm process became an important milestone not only for AMD Company, but also for the entire computer industry. The architectural improvements introduced in Phenom II, their increased clock frequencies and larger L3 cache raised the performance of AMD solutions to a completely new level. As a result, when we tested the first representatives of the quad-core Phenom II X4 family, we could even declare a new round of competition between AMD and Intel in some segments. However, there are not that many segments yet, where they can compete. So far, there has only been fair competition only in the budget quad-core processors market. Phenom II X4 processors from the 800 and 900 lineups seem to be a pretty acceptable alternative to the junior Intel Core 2 Quad solutions, which is a significant step forward for AMD.

 

Of course, the new 45nm Phenom II processor core will allow AMD to stand out in some other market segments. We have already discussed the company’s plans concerning the adoption of 45nm manufacturing technology in CPUs from different market price segments that feature different number of cores, frequencies and L3 cache size. So far these plans have been partially put into life. Namely, Phenom II family already includes not only quad-core models. Besides Phenom II X4 900 and 800 series, AMD is serving the users their “signature” dish – triple-core processors aka Phenom II X3. These CPUs allow AMD to put partially defective quad-core dies to good use offering the customers a very attractive transitional solution. It is, in fact, extremely acute now that the multi-threaded calculations concept is setting in relatively slowly.

From the multi-threaded calculations standpoint, these triple-core processors can barely be regarded as an alternative to any of the Intel offerings. But judging by their prices, Phenom II X3 may be of interest to those users who aim at mainstream computer systems. In other words, it may make perfect sense to compare new-generation triple-core AMD processors against dual-core Intel Core 2 Duo, and the table below illustrates that nicely:

AMD didn’t feel comfortable positioning their Phenom II X3 processors as competitors to top dual-core solutions from Intel, but they considered it absolutely justified to compare them against the junior Intel Core 2 Duo E8000 or top solutions in the E7000 series. Taking into account this situation, we decided to carry out another test session devoted solely to triple-core Phenom II processors. So, our today’s article will discuss the performance and other consumer features of triple-core AMD processors manufactured with 45nm process. Right now they are represented by two Socket AM3 solutions: Phenom II X3 720 and Phenom II X3 710.

Closer Look at Phenom II X3

I have to say right away that the circumstances forced AMD to deliver Phenom II X3 processors to the market. K10 microarchitecture implies that there is a monolithic quad-core die. Phenom II processors manufactured with 45nm process have a pretty big die: 258sq.mm. The production cost for these dies is quite high. For the sake of comparison I can say that Intel uses semiconductor dies that big only in their Nehalem CPUs positioned for the upper price segment. But unfortunately, the current market situation forces AMD has to sell processors at a much lower price, giving up a significant share of the revenue. Putting partially defective dies to good use is a forced measure in this case, as they need to increase the production profitability. That is why we shouldn’t be surprised that Phenom II X3 series emerged so quickly.

Let’s take a closer look at the Phenom II X3 semiconductor die:

Four computational cores take a little over half of the die size that is why the defect is more probable to be found in one of the cores rather than cache-memory. Therefore, AMD offers not only Phenom II X4 800 solutions with smaller L3 cache memory that we have already reviewed before, but also Phenom II X3 700, where one of the cores is disabled right from the start. Thanks to both these series semiconductor dies that for some reason cannot be used in fully-functional Phenom II X4 900 processors will not go to waste.

At the same time, it is pretty funny that the “limited” Phenom II X3 700 processors have L3 cache memory of maximum possible size that is why triple-core AMD processors boast a larger L3 cache than their quad-core counterparts from Phenom II X4 800 series. However, it is not the first time that we are missing the logics in AMD processor characteristics. Another funny inconsistency is that Socket AM3 processors including “limited” Phenom II X3 700 and Phenom II X4 800 clock integrated North Bridge and HyperTransport 3.0 bus at 2.0GHz frequency. At the same time, top Phenom II 940 and 920 models are compatible only with Socket AM2/AM2+ platforms and use 1.8GHz North Bridge and HyperTransport 3.0 bus.

The complete list of currently selling 45nm AMD processors with their specifications is given in the table below. It shows that AMD Phenom II model numbering system that used to be so well-balanced and logical starts getting messed up.

Just like with Phenom II X4 800, one of the key peculiarities of Phenom II X3 700 processors is their Socket AM3 form-factor that is compatible with Socket AM2+ and Socket AM3 mainboards supporting DDR2 and DDR3 SDRAM. However, we have already talked about the new AM3 processor socket and memory controller in our previous review, so now let’s move right to the features and peculiarities of the AMD Phenom II X3 720 processors that we received in our lab:

Phenom II X3 720 is the top triple-core AMD processor available today. One of its most important features that hasn’t been mentioned in the table above is the fact that it belongs to the Black Edition series positioned for computer enthusiasts. It means that Phenom II X3 720 has an unlocked clock frequency multiplier that allows easy overclocking.

When we analyze the specifications of AMD’s triple-core processors, we need to point out that the calculated maximum heat dissipation for Phenom II X3 is set at 95W, which is the same as for Phenom II X4 800 series CPUs. And it immediately suggests that from the power-saving standpoint triple-core AMD processors will lose seriously to the opposing dual-core Intel solutions with only 65W TDP. In other words, AMD’s triple-core concept looks very promising in terms of performance in multi-threaded environments, but the energy efficiency matters seem to become secondary in this case.

However, it is no big news to us. CPUs with three computational cores are not a new trend in the processor market. For almost a year first-generation triple-core Phenom X3 processors based on 65nm semiconductor dies have been available to users. We have already studied all highs and lows of the triple-core CPU design with their help.

That is why there is nothing surprising about the way the triple core Phenom II X3 720 is recognized by the operating system and interacts with applications. The diagnostic CPU-Z utility sees all three cores, too. Here is a screenshot for your reference:

This utility sees Phenom II X3 720 processor as a member of the Deneb family, and although it is quite logical considering that it is based on the same semiconductor die as the 45nm quad-core CPUs, its formal codename is Heka. The manufacturer uses this particular name for their triple-core solutions, however, CPU-Z doesn’t detect this.

Testbed and Methods

Most of our today’s article will be devoted to comparing the performance of Phenom II X3 processors against identically priced dual-core Intel Core 2 Duo. However, in order to draw a more complete picture we have also added the results for the junior quad-core CPUs from AMD and Intel. Besides, we have also included into the summary diagrams the performance numbers for the previous generation triple-core Phenom X3 based on the old 65nm core.

As a result, we used the following hardware and software components to build our testbeds:

Although new AMD Phenom II X4 810, Phenom II X3 720 and 710 processors are designed for Socket AM3 form-factor and support DDR3 SDRAM, we are going to test them in a Socket AM2+ system equipped with DDR2 SDRAM. We made this particular choice of a platform, because these processors positioned for the mainstream price segment will most likely be used in this particular type of systems, because this is the most logical solution from the economical standpoint. Moreover, DDR2 SDRAM was also used in the LGA775 platform that is why it made perfect sense to go with Socket AM2+ for our today’s Phenom II tests.

Performance

General Performance

Overall, the performance numbers for the new-generation triple-core AMD processors are at a pretty expected level. According to SYSMark 2007, Phenom II X3 720 performs about as fast as quad-core Phenom II X4 810 with 200MHz lower clock speed and 2MB smaller L2 cache. The loss of one of the cores causes a serious performance drop only in one single test scenario aka VideoCreation devoted to digital content creation and processing.

At the same time, dual-core Intel competitors cope with this task as well as their triple core rivals. The top Phenom II X3 720 model loses to Core 2 Duo E8400 as well as to Core 2 Duo E7500. It only catches up with Core 2 Duo E7400. So, SYSMark 2007 doesn’t allow us to conclude that an extra core in AMD processors can actually make up for the higher computational efficiency and higher clock speeds of the dual-core Intel solutions.

3D Gaming

The advantages of multi-core processors start showing their best in contemporary games. Looks like three but not two cores has become the optimal choice for the growing number of gaming engines. At least Phenom II X3 outperforms its rivals from Core 2 Duo E7000 series in three tests out of five. Nevertheless, we can also consider Core 2 Duo E8400 to be another good option for games in this particular price range. Compared with the E7000 series, it uses faster bus and has a larger L2 cache. However, AMD solutions are still a little cheaper, so there is more than one choice available to you from the price-to-performance prospective under this particular type of load.

Video Encoding

Video encoding is the type of load that can be very well split into parallel threads. Therefore, new-generation triple-core AMD processors do not leave any chances for the dual-core Intel solutions. However, they also fall far behind the junior quad-core offerings.

Rendering

I could say the same thing about 3D modeling tasks; however, the CPU performance tests performed in 3ds max 2009 cause a little confusion here. Intel processors have always demonstrated high rendering performance in this application due to their microarchitectural peculiarities. As we can clearly see now, the additional core of the new Phenom II X3 720 processors cannot really make up for this. Although Phenom II X3 720 can process up to three computational threads at a time, it is only a tiny bit ahead of Core 2 Duo E840.

Other Applications

Adobe software developers continue optimizing their applications for multi-core architectures. However, in reality it turns out that the most “heavy-duty” filters still cannot really use the advantages of multi-core CPUs. Therefore, dual-core Intel processors with higher clock frequency and individual core efficiency defeat triple- and quad-core competitor solutions.

The things do not look too good in Mathematica 7, too. Although this application learned to split the calculations into parallel thread within a single kernel, dual-core Intel processors work better in this mathematical suite. However, you shouldn’t forget that multi-core processor architecture may come in very handy when there are several kernels launched at the same time.

The WinRAR results correlate in very interesting way. The performance of this archiving utility depends on the number of CPU cores, but is also very sensitive to the cache-memory subsystem configuration. Therefore, dual-core Core 2 Duo E8400 processor with high-capacity and high-speed shared 6MB L2 cache can successfully compete not only with triple-core Phenom II X3 720, but also with a quad-core Phenom II X4 810. As we know, AMD processors yield quite seriously to dual-core Intel solutions from the Wolfdale family in terms of cache-memory subsystem efficiency. At the same time Core 2 Duo E7000 processors with a cut-down L2 cache and slower bus lose to the identically priced AMD solutions.

In Excel the third core of Phenom II X3 processors becomes a sufficient compensation for the microarchitectural advantages of Core over K10, but no more than that.

However, AMD’s triple-core concept wins a real victory in the applications with well-paralleled load that do not depend on the cache-memory subsystem performance that dramatically. And the examples are right here: chess benchmark or Folding@Home are excellent illustrations to this statement.

Power Consumption

Our tests confirmed that Phenom II X3 processors can compete with dual-core competitor solutions when it comes to price-to-performance. Another important integral characteristic of a triple-core AMD processor is performance-per-watt and, frankly speaking, it is of some concern to us, because the core of these processors is much more complex than the Core 2 Duo core. Namely, semiconductor Deneb die that is also used for Phenom II X3, consists of 758 million transistors, while Wolfdale core used for Core 2 Duo CPUs features only 410 million transistors. So, no one expects triple-core AMD processors to prove very energy-efficient. However, to complete the picture we decided to measure the power consumption of a complete system (without the monitor) based on a Phenom II X3 720 processor. We will also compare the obtained results with the power consumption readings taken from other platforms built on processors with similar performance levels.

During our test session we loaded the CPUs using 64-bit version 25.7 of Prime95 utility working in “In-place large FFTs” mode. Moreover, to guarantee correct power consumption readings in idle mode we activated all power-saving technologies, such as C1E, Cool’n’Quiet and Enhanced Intel SpeedStep.

Our concerned proved absolutely justified. Phenom II X3 processors have pretty high power consumption levels although they use cores manufactured with contemporary 45nm production process. Phenom II X3 720 processor consumes considerably more power than 45nm Intel CPUs with two as well as four computational cores in idle mode as well as under maximum load.

So, unfortunately, we can’t recommend the solutions from this processor family for energy-efficient and quiet systems. The competitor CPUs proved to be much better fit for this application.

Overclocking and Fourth Core Activation

45nm manufacturing process used to make Phenom II processors did help the company redeem their honor in the overclocking community. The statistics we have collected so far shows that with traditional air cooling these processors overclock to 3.6-3.8GHz frequencies. So far we haven’t experimented with overclocking of triple-core Phenom II processors, that is why we decided to devote some time to it within our today’s Phenom II X3 720 review.

We performed our overclocking experiments in the same exact testbed as was used for performance tests. I would only like to add that we used Scythe Mugen cooler with a Noctua NF-P12 fan.

Since this CPU belongs to the Black Edition series, we decided to overclock it by simply increasing the multiplier. At the same time I would like to remind you that as we have seen before, the alternative overclocking method by raising the clock generator frequency is just as good, too.

With the processor core voltage increased by 0.2V over the nominal (up to 1.525V), our test processor remained stable with 18x multiplier. We didn’t just increase the multiplier, but also raised the clock generator frequency a little bit, so the maximum frequency our Phenom II X3 720 reached during the experiments was 3.7GHz.

I have to remind you that Phenom II processors use an independent frequency for the integrated North Bridge. The nominal value for this frequency is 2.0GHz, but if you increase the corresponding multiplier to 11x and raise the NB voltage by 0.1V, you can push this frequency to 2.27GHz. We experienced no stability issues at this frequency.

As a result, we can say that the results of our today’s triple-core Phenom II X3 processor overclocking experiments fall within the statistics collected during the overclocking of the quad-core solutions. And actually, it is not surprising at all, because all Phenom II CPUs from AMD are based on the same semiconductor dies.

This is where we could put an end to our story about Phenom II X3 720 overclocking. However, we couldn’t miss the opportunity to check out if the recently revealed information about the way to enable the fourth core was true or false.

Unfortunately, we couldn’t get any of the AMD officials to comment on it. That is why we can only use our practical experience in investigating this matter. And our experience shows that the fourth core of Phenom II X3 processors can really be enabled, and if the particular Phenom II X3 processor is not based on an initially defective core, it may be turned into a fully-functional quad-core CPU. Therefore, it is fairly hard to estimate the probability of success for any core-activation attempts, because a lot depends on the batch the processor comes from and its production time.

In reality, CPUs may act differently during fourth core activation. Some samples simply won’t turn on in quad-core mode, some will start but will fail POST, some will fail only under significant computational load. We were lucky to get our hands on the best Phenom II X3 720 CPU that works just fine in quad-core mode and of course, we couldn’t miss this great opportunity to run even more tests.

The fourth core in Phenom II X3 processors can be activated very easily without any hardware modifications. All CPU computational cores will get automatically activated when you enable Advanced Clock Calibration (ACC) in the mainboard BIOS Setup.

It means that you will be able to activate all cores of your triple-core CPU only if your mainboard is based on an AMD chipset with SB750 South Bridge. The necessary functions are available in the BIOS of almost all mainboards built on AMD 790FX and 790GX. For our tests we used a Gigabyte GA-MA790GP-DS4H mainboard that enabled the fourth core of our Phenom II X3 720 processor in a wink.

Even though the processor model name was displayed in a slightly strange way during POST:

It worked impeccably in the operating system.

There is only on strange observation that I would like to share with you. During our tests with the fourth core activated CPU temperature monitoring stopped working. All diagnostic utilities reported that the processor core temperatures were 0°C.

However, it didn’t affect the system stability or performance in any way. Moreover, further experiments showed that quad-core Phenom II X3 720 could also be overclocked. The CPU was unstable at 3.7GHz that we had reached in triple-core state, but once we lowered the clock speed just a little bit, all stability issues were gone.

As you can see from the screenshot above, our triple-core Phenom II X3 720 worked stably as a quad-core processor at 3.67GHz frequency. Of course, this potential opens massive opportunities for those users who prefer to have their hardware run way beyond the manufacturer specifications.

Phenom II X3 720 vs. Core 2 Duo E7500 during Overclocking

Looks like Phenom II X3 720 could be a very attractive choice for overclocking fans. Without any sophisticated cooling solutions this CPU can be overclocked 33% above its nominal clock speed, and if you are lucky, you might also get an additional fourth core.

However, the closest competitor from the pricing standpoint, Intel Core 2 Duo E7500, is also no fool. This CPU based on 45nm Wolfdale core features tremendous unutilized frequency potential. For example, a randomly selected CPU overclocked in no time to 4.2GHz. And all we had to do was to increase the core voltage to 1.425V and to raise the FSB frequency from 266MHz to 382MHz.

This significant overclocking potential of Core 2 Duo processors may make overclockers think twice about the most optimal choice for their needs. In nominal mode when Phenom II X3 720 offers very good performance compared with Core 2 Duo E7500, the frequency difference between them is only 5% in favor of the latter. Once you overclock both of them, Intel processor - that usually overclocks better – will boast 13% higher frequency than the AMD solution. This change in the frequencies may affect the overall picture that is why we decided to perform one more test session revealing which CPU performs better during overclocking.

As you see from the table above, the situation doesn’t really change after we overclocked both processors. AMD Phenom II X3 720 remains the leader in those tasks where its three cores secured its victory over the dual-core competitor in the nominal mode. The only application when the leadership changed is 3ds max 2009 rendering suite, where better overclocking to 4.2GHz let Intel CPU surpass Phenom II X3 working at 3.7GHz frequency. So, we can conclude that Phenom II X3 720 doesn’t lose its ground during overclocking.

However, do not forget that if you are lucky, your Phenom II X3 720 may transform into a quad-core processor that can be overclocked almost to the same heights. In this case, it will totally defeat Core 2 Duo E7500 in most tests.

We really wish that you could enable the fourth core in all triple-core AMD processors. But even without it Phenom II X3 looks like a very good overclocker CPU that doesn’t yield to similarly price Intel solutions, such as Core 2 Duo E7000, in terms of hidden performance potential.

Conclusion

I doubt that anyone will argue that all currently produced AMD Phenom II processors boast very attractive price-to-performance ratio. Triple-core representatives of this family, Phenom II X3, are also no exception. They are very interesting solutions in their price range and their triple-core architecture offers noticeably higher performance during multi-threaded load than dual-core Core 2 Duo E7000 with similar price tags. Since multi-threaded computing gets better adopted by various software developers, including game developers, of course, triple-core processors become faster than their dual-core rivals in a significant number of tasks.

Phenom II X3 processors can also be of great interest to computer enthusiasts. They offer not only good frequency potential that is sufficient for successful competition against overclocked Core 2 Duo CPUs, but also may become quad-core with certain amount of luck on your side. This undocumented feature allows enabling the blocked fourth CPU core that with some probability may turn out fully functional. So, taking into account the possibility to use Phenom II X3 in modes other than the officially defined by the spec, it may deliver an impressive performance boost and hence step up to the level of higher-priced solutions.

In fact, the only immediate weakness of the Phenom II X3 CPUs is their power consumption. These processors are absolutely unfit for energy-efficient systems. Three cores and relatively high core voltage make them yield not only to dual-core Intel solutions from the same price range, but also to entry-level quad-core CPUs. So, the transition to 45nm process didn’t make Phenom II processors, and especially triple-core ones, an attractive choice from the performance-per-watt standpoint.

Summing up everything we have just said we have to admit that if we disregard the power consumption issues, then AMD does have a very good 45nm alternative to dual-core competitor’s solutions in the mainstream price segment. However, despite the microarchitectural improvements, adoption of the new production process, higher clock speeds and DDR3 SDRAM support, AMD is still behind the top dual-core competitor solutions on the performance scale. And it means that as time passes, things will get harder for AMD in the processor market, especially when Intel launches their low-cost 32nm Nehalem CPUs in the end of this year.