by Ilya Gavrichenkov
12/19/2007 | 05:35 PM
The end of the year is traditionally considered the best time to sum up the results, analyze the achievements of the past year and make plans for the new year to come. That is why with Christmas holidays approaching articles covering the overall market situation become especially acute. So, we were planning this article to kind of sum up in a single test session all the processors released in 2007, which has every right to be regarded as the beginning of quad-core era. Over the past year the prices on processor with four computational cores have dropped down to pretty acceptable levels thus increasing their popularity among computer enthusiasts very rapidly.
However, the main characters of our today’s article turned out new quad-core AMD processors from Phenom family, which very first models were announced on November 19, 2007 and which already start selling in computer stores. However, it is not their unprecedented consumer qualities that determined out specific interest to these processors today. The thing is that Phenom processors that were initially scheduled to be released about a year ago, seem to be AMD’s desperate attempt to regain the title of the high-performance processor maker that they had to give up under Intel’s devastating invasion with extremely successful CPUs on Core micro-architecture being offered for over a year and a half already.
Phenom’s success is almost a matter of life and death for AMD. The company’s financial situation has been aggravating lately, because their old K8 micro-architecture has turned almost completely uncompetitive. AMD expects their new processors based on improved K10 micro-architecture to improve the current situation in the market for them. But will they really succeed in turning things around? – This is the question our today’s article will try to answer for you.
Although almost a month has passed since AMD Phenom CPUs have been officially launched, it is only now that we got the chance to compare them fully against their direct competitors. The thing is that AMD didn’t send out their processor samples to reviewers having offered to replace traditional independent research with on-site test session in their own mobile lab set up specifically for the members of the press on the launch day. These are exactly the results you will find on majority of web-sites out there. We decided not to publish preliminary data like that and waited patiently for the chance to get our hands on the new solution for a complete and unbiased investigation.
Luckily, AMD helped us by providing an engineering sample of their Phenom processor, which will be the main hero of our today’s discussion. However, before we get into details on the actual benchmark results, we have to say a few words about all those innovations they introduced in the new processor family. Phenom processors boast not only different micro-architecture than their predecessors. AMD positions Phenom as a part of their new Spider platform that also includes new AMD 700 chipset series, and ATI Radeon HD 3800 graphics accelerator family.
No matter what the outcome of our today’s test session is going to be, we cannot deny that AMD managed to outpace Intel with the launch of a true quad-core processor. While, Core 2 Quad processors manufactured with 65nm and 45nm process are none other but two dual-core processors combined together in a single package, Phenom is a fully-fledged quad-core solution. This processor die (currently manufactured with 65nm production process) contains four cores at the same time.
This AMD’s approach to multi-core processor design allowed company engineers to implement functional units shared between all four cores. These are the units implemented one of each in the new AMD Phenom: controller for HyperTransport bus that serves to transfer data from CPU to the chipset, DDR2 memory controller and L3 cache. AMD has already used a shared HyperTransport bus and memory controller in their dual-core Athlon 64 X2 processors before. So we were not surprised to see them in the new AMD Phenom, too.
The shared L3 cache, however, is being used for the first time. The current Phenom models have a 2MB L3 cache. The bandwidth of this cache is not very high compared with the memory subsystem performance, however it boasts pretty low latency. Moreover, it allows to significantly speed up the data transfer rate between the processor cores without loading the memory bus: this is actually its major purpose in the new processors.
However, putting four processor cores onto a single dies also has a negative side to it. The thing is that these semiconductor dies, even manufactured with contemporary 65nm process, come out pretty big in size. Of course, it leads to significant drop of the chip yields and increase in production costs. However, AMD seems to have found a way to put most of the defective dies to good use. Next year they will start supplying triple-core and maybe even dual-core processors manufactured from original Phenom dies with one or two failed cores.
Another issue resulting from large die size of the new processors is their relatively low clock frequencies, because they have to watch out for growing heat dissipation of the CPU. While quad-core Intel processors manufactured with 65nm process are currently running at up to 3.0GHz speeds, AMD will hardly be able to introduce a Phenom with the clock frequencies beyond 2.6GHz in the nearest future. Moreover, the currently announced models work only at 2.2GHz-2.3GHz. It looks like they will be able to resolve this issue only in H2 2008, when AMD is planning to switch production of their quad-core processors to more advanced 45nm manufacturing technology.
So, it’s time to compare the basic specifications of the new Phenom processor against those of its main quad-core opponent – Core 2 Quad from Intel. The table below shows two Intel Core 2 Quad models: the old one codenamed Kentsfield and a new one codenamed Yorkfield manufactured with 45nm process and scheduled to become widely spread in early 2008.
New Phenom processors are extremely interesting not only due to their four processor cores on a single die. AMD engineers managed to introduce a number of improvements into the actual micro-architecture thus making the actual cores work faster (compared with the Athlon 64 processors). And although core micro-architecture in Phenom processors doesn’t differ too much from the classical K8 micro-architecture, AMD used a new codename for it: K10 - that was later replaced with a more poetic “Stars Microarchitecture”.
We have a separate article on our site devoted to all the details of the revised micro-architecture. So here we are going to briefly list all the innovations made in the AMD Phenom processors:
Together with a few changes in the core micro-architecture, AMD engineers paid special attention to modifying the interfaces Phenom CPUs use to communicate with the rest of the world. First of all I would like to point out faster HyperTransport bus that meets specification version 3.0 in the new processors. While Athlon 64 processors used HyperTransport bus with 8GB/s bandwidth, Phenom may exchange data with the chipset at 14.4-16.8GB/s speed. Moreover, HyperTransport 3.0 spec also allows to additionally increase the bus bandwidth to 20.8GB/s, which will evidently be implemented in the upcoming quad-core processors.
Faster bus between the processor and the chipset may also be important for those systems where multiple graphics cards are installed. That is why HyperTransport 3.0 support became one of the primary distinguishing features of the Spider platform. This new platform supports Crossfire configurations built with two, three and four graphics accelerators.
At the same time, HyperTransport protocol versions are backward compatible, so you can use Phenom processors in old mainboards built on chipsets supporting only the previous HyperTransport 2.0 bus.
However, we shouldn’t overestimate the importance of HyperTransport 3.0 bus support in the new Phenom processors. Since AMD CPUs feature an integrated memory controller, the bandwidth of the bus between the CPU and the chipset matters only in “heavy-duty” graphics applications.
As for the memory controller, it also got a few things improved in the new Phenom processors. Although new AMD CPUs, continue working with DDR2 SDRAM, just like their predecessors, AMD engineers provided Phenom with DDR2-1066 modules support, as well. However, in order to meet JEDEC standards, DDR2-1066 memory can only work in Phenom platforms with pretty “weak” timings of 4-5-5-15 or higher.
The second peculiarity of the integrated memory controller is the fact that it is implemented as two independent 64-bit controllers rather than a single 128-bit interface. This allows the memory of Phenom platforms to work in two modes: ganged and unganged. The first one is analogous to the usual 128-bit dual-channel mode. The second one implies that the CPU can deal with two independent 64-bit memory controllers thus processing two memory requests simultaneously, which is good for multi-threaded environments.
Phenom memory controller is also interesting because it runs at a different frequency than the CPU clock: it uses its own clock frequency multiplier and runs at 2GHz on all currently available CPU models. They did it this way to ensure that the actual memory frequency always matches the desired one, which was not always the case with previous generation AMD processors. They frequency was obtained by applying integer dividers to the CPU clock speed value. So, the Phenom memory controller may set the DDR2 SDRAM frequency at exactly 400, 533, 667, 800 or 1066MHz at any clock speeds.
Cool’nQuiet technology in Phenom processors got to a completely new level, too. Now they call it Cool’n’Quiet 2.0. It allows to independently adjust the power consumption and frequency of all four processor cores and memory controller.
Moreover, Phenom also supports C1E state that takes place for the processor after a few milliseconds of idling. In this case the CPU not only drops down its clock speed, but also reduces the HyperTransport and system bus power consumption.
Another new and pretty interesting feature of the Cool’n’Quiet 2.0 technology is the ability of the CPU voltage regulator to receive data on the current power-saving CPU mode. Theoretically, it allows adjusting the voltage regulator circuitry parameters interactively depending on the processor operational conditions. I believe that mainboard developers will be able to implement corresponding algorithms in their solutions.
Unfortunately, because of the new HyperTransport 3.0 bus, Cool’n’Quiet 2.0 technology and new memory controller features AMD had to modify the processor socket design. Phenom processors should formally fit into the new sockets called Socket AM2+. Only in the mainboards using the new type of processor socket, Phenom can truly show its potential. The good news is though that Phenom CPUs are also compatible with old Socket AM2 mainboards: there are no dramatic mechanical or electrical differences between Socket AM2 and Socket AM2+. However, when you install Phenom into old mainboards, it will lose some of its features, such as DDR2-1066 SDRAM support, individual voltage adjustment for processor cores and memory controller, and HyperTransport 3.0 support. Of course, it will have its negative impact on the performance and power consumption rates, but will allow to easily modify old platforms built with single-core and dual-core Socket AM2 CPUs.
Phenom lineup currently includes two models: Phenom 9500 and Phenom 9600. The table below shows the specifications of these processors:
4 x 512KB
4 x 512KB
After December 19, 2007 Phenom 9600 2.3GHz is going to be available in two modifications: besides the regular CPU AMD is also offering the so-called Phenom 9600 “Black Edition” aimed at overclocking fans and featuring an unlocked clock frequency multiplier. Actual retail price for Phenom 9500 and 9600 processors are quite democratic overall and rest at around $200 and $245 respectively.
Further frequency growth will be tied up to introduction of the new CPU core stepping. It should not only increase the frequency potential, but is also expected to have some of the currently existing bugs eliminated. In particular, it should eliminate the notorious “ERRATUM 298” bug in the TLB block of L3 cache that can theoretically cause the system hang under heavy workload and in case virtualization technology is activated.
In Q1 2008 the company is planning to launch Phenom 9700 with 2.4GHz speed and $300 price tag and Phenom 9900 running at 2.6GHz and priced at less than $350. Moreover, Phenom 9900 will not only work at higher frequency but will also feature faster HyperTransport bus (it should hit 4GHz speed) and faster memory controller. However, higher clock speeds will inevitable affect the processor heat dissipation. The preliminary data suggest that Phenom 9700 TDP will be set at 125W, and Phenom 9900 TDP – at the maximum allowed for Socket AM2+ 140W.
Of course the innovations introduced into the new AMD Phenom processors, at least those that deal with external interfaces, require appropriate chipset support. That is why Phenom processor launch was also accompanied with the announcement of the new “seventh series” AMD chipset family. There are three solutions in this series: AMD 790FX (RD790), AMD 790X (RD780) and AMD 770 (RX780). Their main peculiarity is the fully-fledged support of the new processors, namely, full compatibility with the new Socket AM2+. In other words, new chipsets work with HyperTransport 3.0 bus and mainboards based on them support DDR2-1066 and allow independent powering of the memory controller and processor cores.
Moreover, the new AMD chipsets were designed to meet contemporary graphics cards requirements, too. Here I am talking about high-speed PCI Express 2.0 interface support: new AMD chipsets have it fully implemented.
Of course, even thought the new Spider platform is naturally compatible with Nvidia based graphics accelerators, it is primarily targeted to accommodate AMD graphics solutions. That is why it is absolutely logical that the top chipsets support Crossfire technology. Moreover, AMD 790X can support this technology as PCI Express x8 + x8, and the top of the line AMD 790FX offers full-speed PCI Express x16 + x16 mode. Each of the graphics busses in 790FX may be split into two PCI Express x8 busses. This way they can build mainboards with four graphic slots each.
AMD offers a pretty old SB600 microchip as the South Bridge for the new chipsets. Unfortunately, its features do not look that appealing any more: it supports only ten USB 2.0 ports and four Serial ATA II channels.
However, AMD promises to replace this chip with a more up-to-date SB700 very soon. It should support 12 USB 2.0 ports and 6 Serial ATA II channels.
Mainboard makers welcomed AMD in the chipset market with solutions for their own processors with great enthusiasm. In the nearest future all leading board manufacturers will start shipping their solutions based on AMD 790FX, AMD 790X and AMD 770. Here I have to stress that AMD will insist that everyone sticks to their pretty smart price policy: contemporary mainboards for Phenom processors will be undoubtedly cheaper than analogous solutions for Intel CPUs.
Another advantage of the new AMD chipsets is their low heat dissipation, because they are manufactured with the most advanced 65nm process. For example, the typical heat dissipation of the AMD 790FX North Bridge will be about 10W, which is a few times lower than what the other manufacturers’ chipsets have to offer.
Aiming their new Spider platform for computer enthusiasts, AMD couldn’t help pleasing the overclocking fans with a little something. They introduced new AMD Overdrive utility for hardware monitoring and systems management on platforms with Phenom processors and AMD seventh series chipsets. This utility provides detailed info on the parameters of the system processor, memory and mainboard; helps monitor main system voltages and temperatures; adjust working frequencies of the processor cores, memory controller and other busses; change memory timings. Moreover, AMD Overdrive also offers a built-in system stability and performance benchmarks.
To check out the new Spider platform, namely the new quad-core Phenom processors from AMD, we received a test kit including AMD 790FX based mainboard and a new CPU sample.
The processor we got was formally presented to us as Phenom 9900 with an unlocked multiplier (2.6GHz clock frequency). However, we cannot really determine what particular model that is. Identification string reads that it is an engineering sample and the CPU clock frequency multiplier is unlocked.
The CPU is based on B2 core stepping – the only core stepping used for mass processor as of today.
The processor making doesn’t make things any clearer for us either. The only thing it reveals is that the processor we received is designed to work at 1.3V Vcore.
By the way, note that this processor looks very similar to Athlon 64: packaging, pin layout and heat-spreader remained exactly the same.
As for the mainboard, we received our engineering Phenom sample together with an Asus M3A32-MVP Deluxe based on AMD 790FX chipset with SB600 South Bridge.
This mainboard is positioned as a solution for computer enthusiasts, that is why Asus engineers had to add a number of onboard controllers to make sure that it meets certain requirements for a product of this category. Thanks to two additional Marvell SATA controllers, Asus M3A32-MVP Deluxe offers not four but six SATA II ports with RAID support and an eSATA port. Besides 10 USB 2.0 ports, the board also comes with two IEEE1394 connectors implemented via an agere controller.
However, although the expansion features of Asus M3A32-MVP Deluxe are definitely quite exciting, it is remarkable for fully-fledged support of all new functions introduced in the AMD Spider platform.
The board is equipped with four PCI Express x16 slots. As the chipset suggests, slot pairs automatically switch to PCI Express x8 logical mode when active. However, the third and the fourth graphics slots are placed very close to one another, which will, unfortunately, prevent you from using one of them with powerful graphics cards in Quad Crossfire configurations. In other words, the mainboard is very well optimized for up to three graphics cards, but nevertheless, may still work with four with certain allowances, of course.
Asus M3A32-MVP Deluxe has a fully-fledged Socket AM2+: it supports HyperTransport 3.0 with higher bandwidth. Moreover, the processor voltage regulator design is also quite interesting: it is a ten-phase circuitry. Its 8-phase part powers the CPU while the additional two phases serve to power the memory controller built into the processor.
Processor voltage regulator circuitry uses mostly reliable capacitors with polymer electrolyte. MOSFET, chipset North and South Bridges use a single cooling system with heat-pipes. The main copper-colored heatsink of this cooling system is made of solid aluminum and is located right behind the processor socket. The mainboard comes with a special centrifugal rotor fan that can be installed on top of this heatsink. Despite low heat dissipation of the new AMD 790FX chipset, this entire cooling system heats up a lot: looks like the CPU voltage regulator is the main heat source on the board.
Since Socket AM2+ is mechanically the same as the traditional Socket AM2, Asus M3A32-MVP Deluxe mainboard is compatible with usual AMD processor coolers. However, you don’t have much of a freedom on this board, because the memory slots and the voltage regulator heatsink are placed very close to the processor socket. Another drawback of the PCB layout is the absence of additional fan connectors around the processor socket.
As for the BIOS Setup, computer enthusiasts should be very pleased with it. The board allows adjusting all necessary frequencies and voltages and features special tools for flexible memory controller configuring.
Thanks to the unlocked clock frequency multiplier, the Phenom processor sample we had at our disposal was tested at frequencies from 2.2GHz to 2.6GHz that correspond to the default speeds of 9900, 9700, 9600 and 9500 models. These are the CPUs that already are or will be available in the near future.
The new AMD Phenom will compete against Core 2 Quad Q6600 and Q6700 processors – Intel’s quad-core solutions priced the closest. Here you should note though, that Core 2 Quad Q6700 processor is currently still much more expensive than any of the AMD Phenoms.
However, the situation should change in Q1 2008 when Intel is going to launch a few new quad-core processor models manufactured with 45nm process. That is why we have also included the results for a promising Core 2 Quad Q9450 that will cost a little over $300. So far this processor also known as Yorkfield and running at 2.6GHz frequency is not available yet, bit should be by the time Phenom 9900 and 9700 come out.
Moreover, we completed the picture by adding the results of the top dual-core AMD and Intel processors.
As a result, we had the following platforms participating in our test session:
Phenom overclocking tests is another interesting part of our today’s discussion. Although it was an engineering sample, the obtained results may serve as a preliminary reference indicating what we could expect from overclocking of quad-core AMD processors with B2 core stepping.
Overclocking experiments were performed in the same testbed as the performance tests. The processor was cooled with Scythe Infinity cooler. System stability was checked with Prime95 utility.
The default processor Vcore for our sample was 1.3V. Without pushing it any higher we got it to run stably at 2.8GHz.
Having increased the voltage to 1.45V, we managed to get our processor to work at 3.0GHz, however, the system stability was pretty questionable at first. Unfortunately, further voltage increase didn’t improve the stability, but we just couldn’t give in so easily, as we were very curious to see what the Phenom could do at 3.0GHz. Luckily, our processor proved capable of running flawlessly at this speed. As we found out later, it was failing because of insufficient second voltage that can be adjusted independently on Socket AM2+ mainboards. Once the voltage of the memory controller and HyperTransport bus was raised from the default value to 1.25V, the system passed all stability tests impeccably.
Of course, we couldn’t pass on checking out the 3.0GHz Phenom performance. Therefore, the diagrams in the next part of our review will contain not only the results for Phenom 9500, 9600, 9700 and 9900, but also the performance of the overclocked processor.
SYSmark 2007 testing suite uses typical work scenarios in the most popular applications and tasks.
As you can see after the first few benchmarks, AMD quad-core processors cannot hope for a successful revenge. Despite its improved micro-architecture and true quad-core design, Phenom loses to Core 2 Quad CPUs. Only the overclocked to 3.0GHz Phenom processor can compete with the youngest Core 2 Quad Q6600 from Intel. However, you shouldn’t forget that AMD has not plans to release mass processors with clock speed like that any time soon.
The situation is not very rosy for AMD in games as well. The results obtained in contemporary applications of this type suggest that even the promising Phenom 9900 cannot ensure the same performance level you can get from Core 2 Quad Q6600.
By the way, Phenom doesn’t look too good even compared with the predecessor – Athlon 64 X2 6400+. The 1GHz clock speed difference and pretty weak optimization for quad-core architecture make dual-core AMD processors parctically as efficient in games as the new quad-core ones.
Overall, the results are what we expected them to be: AMD cannot boast victory during audio and video content encoding.
However, the diagrams above also have a few exceptions. As we see, Phenom processors cope pretty well with H.264 encoding, at least their relative result in this test is much better than in all other cases. I can even state that the new quad-core AMD processors prove worthy rivals to Core 2 Quad. The FPU and SSE unit improvements introduced in the new AMD CPUs seem to have paid back under a certain type of workload. Nevertheless, the upcoming Core 2 Quad processors based on 45nm cores will also improve the performance of the Intel processor family. As a result, Phenom may no longer feel competitive even in this application in the near future.
We would also like to say a few words about Phenom’s defeat in iTunes test. The lag is significantly greater here. It must be the fact that integer units in the new Phenom processors that are actively involved into mp3 decoding process have hardly been improved in any way compared with the Athlon 64 processor family.
The overall picture here is very similar to what we have already discussed. Although the monolithic design of the new Phenom processors ensures more efficient communication between the cores than the dual-die Core 2 Quad, the performance difference between the quad-core AMD and Intel processors is still more than significant.
For this part of our test session we selected another four widely spread applications, which do not fit into any of the previous parts.
But the diagrams do not reveal anything principally new: performance will not make Phenom popular. Now the hope rests with the smart pricing policy.
To investigate the consumer potential of the new quad-core AMD processors to the full extent, we couldn’t avoid checking out their power consumption rates. I would like to stress that this is preliminary data because it was obtained on an engineering sample.
During our tests we compared the power consumption of the above described test platforms equipped with different processors: AMD Phenom and Intel Core 2 Quad. We measured the current going through the processor voltage regulator circuitry, thus estimating the power consumption of the CPUs themselves (not taking into account the losses inside the voltage regulator). The processors were loaded using Prime95 25.5 utility.
Enhanced Intel SpeedStep and Cool’n’Quiet 2.0 power-saving technologies were activated. Our Phenom CPU dropped its clock speed to 1.3GHz and its Vcore - to 1.05V in idle mode.
The diagram below shows results obtained in idle mode and maximum CPU utilization created with different number of threads (from one to four). This approach should show how efficient is Cool’n’Quiet 2.0 that can manage Phenom processor core frequencies independently.
Unfortunately, Phenom processors cannot boast low power consumption rates. Core 2 Quad Q6600 that is on average about 7% faster than Phenom 9900 consumes less power in idle mode as well as under workload. Although the Phenom power consumption curve shows that Cool’n’Quiet 2.0 actually works fine, it is not enough to beat the competitor from the energy-efficiency standpoint. Intel solution remains one of the best choices from the performance-per-watt prospective.
I believe many of you remember the triumph of the first 64-bit x86 Athlon 64 processors. They were the ones that made AMD processor leader for a significant period of time: until Intel started rolling out their CPUs on Core micro-architecture. It was then that AMD’s era of success came to an end and hard times set it. For over a year and a half AMD fans hope for the new solution to finally come out that will help this company regain their high-performance maker title. That is why Phenom is one of the most impatiently awaited solutions of the year 2007. Numerous hopes were pinned upon it.
And finally the waiting is over. The curtain of mystery has been raised over the new AMD Phenom processor and we a chance to check out this achievement using bare facts and figures. Which will hardly please those of you who expected this processor launch to change the CPU market dramatically. Despite all indisputable advantages and technological innovations, Phenom processors available today and scheduled to come out later will hardly be able to compete successfully with quad-core Intel CPUs. Especially, with those that will belong to 45nm Yorkfield generation.
The performance of quad-core AMD Phenom processors based on K10 micro-architecture that is none other but enhanced and modified K8 micro-architecture proved considerably slower than any other quad-core processors from Intel Core 2 Quad family. That is why it would make perfect sense for AMD to position their new Phenoms as mainstream solutions. In other words, as budget CPUs with four computational cores.
This is actually the current AMD’s strategy already. Phenom 9500 and 9600 processors are selling at considerably lower prices than any Core 2 Quad solutions. The current retail price difference between Phenom and Core 2 Quad does reflect the fact that Phenom 9500 is 17% slower and Phenom 9600 – about 14% slower than their competitor.
So, it looks like Phenom CPUs will not win the enthusiasts’ hearts just yet. Although they can overclock pretty well, they can only catch up with Core 2 Quad working in nominal mode at best. Therefore, even the launch of Phenom 9600 “Black Edition” with an unlocked multiplier will hardly create any additional interest among computer users.
The power consumption of the new Phenom processors is also not among their advantages. They require more power than their faster competitors, which makes them less attractive from the performance-per-watt prospective.
Summing up everything we have just said, I can conclude that Phenom has very vague market prospective. At this time they may be interesting only as inexpensive quad-core solutions used to upgrade the existing Socket AM2 platforms. Especially, since AMD made them compatible with the existing infrastructure. Also, they will most likely win some fans due to their low price. However in any case, AMD shouldn’t hope that the demand will grow massive.
In this situation AMD should focus on increasing the clock speeds of their new processors, because they no longer have the chance to offer a CPU with more advanced micro-architecture in the near future. Especially, since the today’s gap between the top Phenom and Core 2 Quad is almost 1GHz. However, Phenom CPUs with 3GHz+ speeds will hardly come out before they switch production to 45nm process that is scheduled to occur only in H2 2008.