The Single-Decker Champ: ATI Radeon HD 3870 X2 Graphics Card Review

ATI Radeon HD 3870 graphics card proved to be a really popular option for performance-mainstream market. But AMD wants to target the high-end using the same technology, but this time with two ATI RV670 chips. Let’s find out whether the new ATI Radeon HD 3870 X2 is actually faster than its rivals from Nvidia camp.

by Alexey Stepin , Yaroslav Lyssenko, Anton Shilov
02/18/2008 | 10:44 AM

We were pleased with the ATI Radeon HD 3870 and Radeon HD 3850 graphics cards we reviewed recently, yet the positioning of the HD 3870 model left us somewhat disappointed. Instead of pitting it against the GeForce 8800 GT 512MB, AMD refused to compete with Nvidia altogether. This has become a tendency already.

 

In early 2006 ATI Technologies used to be the leader in terms of performance and price of its solutions. The ATI Radeon X1900 XTX cost $649 and delivered the highest performance available in the first half of 2006. It is still considered a top-performance product. Later there appeared the ATI Radeon X1950 XTX for $449 which was not far inferior to Nvidia’s dual-chip GeForce 7950 GX2 that cost $649. But finding itself to be late with the release of the ATI Radeon HD 2900 XTX, AMD didn’t spend resources to accelerate this solution. The company just lowered the price of that flagship product to $399 positioning it as an opponent to the modest GeForce 8800 GTS rather than to the top-end GeForce 8800 GTX/Ultra. The ATI Radeon HD 3870, issued in late 2007, became formally the new best product from AMD and it cost $219, i.e. only one third of the price of the fastest Radeon of 2006.

AMD is likely to put the tag of $399 on the upcoming Radeon HD 3800 X2. This will raise the average price of an AMD graphics card somewhat higher, yet will hardly lift the company’s reputation up as a maker of top-performance and expensive products. Considering that the market share of the Radeon series has been shrinking and the non-graphics assets of ATI Technologies have been profitable, this is a discouraging, but not surprising, situation.

Of course, few people actually buy graphics cards for $649 and more, but such products draw the spotlight to the company as well as to the trademark. The necessity of offering a wide range of graphics solutions is the main reason why there are only ATI and Nvidia left on the market of discrete graphics hardware while the others – 3dfx, 3Dlabs, Matrox Graphics, Trident Graphics, S3 Graphics, XGI – have vanished or exist but formally.

Refusing to release a really notable flagship product and lowering prices for its top-performance cards, AMD has been actually curtailing its graphics card series.

The new Radeon HD 3870 X2 brings AMD’s graphics department back to the position it held in the middle of 2006 when they could offer the fastest graphics card at $449. In this review we will see if this product can restore the company’s reputation among enthusiasts.

Multi-GPU Technology: Improvements and Drawbacks of the Concept

Creating multi-GPU products seems to be a simple and elegant way to boost performance when the GPU developer doesn’t have a new chip that would be able to do that alone. This solution has its downside, though. We don’t even mean such technical problems as compatibility with games. These are very important too, but we’d want to mention the economical aspect. Multi-GPU solutions limit the manufacturer’s freedom of price maneuvering, which is not good for the end user who has to buy less fast products for a higher price than he could buy otherwise. We’ll explain this now.

The benefits of the classic approach can be illustrated with historical examples, one of the most striking ones being the R300 core. It was employed on a whole family of graphics cards, from mainstream to top-performance. ATI Technologies could put defective cores to use by disabling faulty subunits to create rather inexpensive graphics cards that would deliver about half the performance of the full-featured product (Radeon 9700). On the other hand, when this core was eventually perfected, it could be clocked at a higher frequency, which helped increase its performance by 33% (Radeon 9800 XT). The same core, in cut-down form, was installed on a number of inexpensive cards: Radeon 9550, 9600, X300, X550, X600, and X1050. Thus the same GPU design with minor changes covered all price segments from $150 to $500.

ATI’s R420/423 core can boast just as impressive a history. Originally used in the Radeon X800 series, it was later slightly redesigned into the faster and more expensive R480/R481 (Radeon X850 XT) and, after the transition to 110nm tech process, into the affordable R430 (Radeon X800 XL). The cut-down version of the core, the RV410 chip, was installed on the Radeon X700 graphics card. In other words, ATI again managed to fill the entire price range with what was virtually the same GPU design.

The introduction of modular architecture made the process even simpler and the next graphics core, the R520 chip, gave birth to a large number of products, from the cheap Radeon X1300 (RV515) to the DirectX 9 king Radeon X1950 XTX (R580+).

The company cut the manufacturing costs while the customer was offered the opportunity of broader choice. This price maneuvering could hardly be possible if ATI Technologies switched to multi-GPU technologies instead of modifying and perfecting one chip. It also wouldn’t be good for the customer who’d have to buy products with lower performance for more money. Thus, dual-chip graphics cards can only represent a tactical move in order to win some time necessary to develop a next-generation core that would ensure a new level of performance. It doesn’t matter if this core is going to be a single chip or a multi-chip module (MCM). An MCM is similar to Intel’s quad-core processors Core 2 Quad which are two individual dual-core chips in a single package. ATI is expected to use the MCM concept in the next-generation GPU codenamed R700.

So far, the RV670 core is the best the former ATI Technologies can offer. It is a good core, yet inferior to the Nvidia G92 in performance. Combining two such cores on a single PCB to create a new high-performance graphics card is largely a forced solution as AMD’s graphics department hasn’t been offering anything competitive in the $300-400 category for a long time. The Radeon HD 3870 X2 is meant to break the tendency and show that the company can challenge its opponent in the premier league of single graphics cards where the Nvidia GeForce 8800 Ultra has been reigning for what seems like ages already. So let’s see what AMD/ATI can offer to a demanding gamer now.

ATI Radeon HD 3870 X2: Work Principles

Here are the specifications of the ATI Radeon HD 3870 X2 card in comparison with Nvidia’s counterparts:

In fact, the new card is no different, except for GPU and memory frequencies, from two Radeon HD 3870 card working in CrossFire mode. Theoretically, the ATI Radeon HD 3870 X2 boasts a huge potential and should be competitive against the GeForce 8800 GTX/Ultra as well as GeForce 8800 GTS 512MB, yet you can never be sure with multi-GPU solutions. You can only see what they are capable of if you test them in real 3D applications. But before we test the new card, we are going to see how it is designed.

The two RV670 GPUs are joined together one a single PCB in CrossFire mode by means of the Compositing Engine available in each graphics core. This engine used to be external in earlier versions of CrossFire and implemented by means of a Xilinx Spartan-3 FPGA. It was first integrated into the graphics core in the ATI RV570 chip, installed on the Radeon X1950 Pro. The logical scheme of CrossFire looks like this:

Here, each GPU has its own PCI Express bus. It means the mainboard must have two PCI Express x16 slots and the chipset must support CrossFire technology. This support is only implemented in AMD’s and Intel’s chipsets, but not in Nvidia’s, which doesn’t suit the ATI Radeon HD 3870 X2 as it is positioned as a single graphics card. Of course, it is expected to work with both its graphics cores on any mainboard with any chipset.

There have been attempts to create a universal multi-GPU solution that needs only one expansion slot since 2000. We can recall the ATI Rage Fury Maxx that became the victim of faulty software AFR and overall buggy drivers. The last attempt by Nvidia was more of a success. Working on its GeForce 7900 X2 and later on GeForce 7950 X2, the company tried to solve the problem of inter-GPU communication and compatibility by means of a special PCI Express x48 switch. It looked like that:

Alas, Nvidia did not achieve full compatibility: its graphics card would not start up on some mainboards. The company’s website even had a special page that listed certified mainboards the GeForce 7950 GX2 was guaranteed to work with. Besides that, the old trait of Nvidia SLI technology, its dependence on the software part, was conspicuous, too: the performance of the card could plummet to the level of a GeForce 7900 GT or even lower if the particular game was not explicitly supported in the driver.

That solution had a potential, however, and Nvidia could have spent time and money to polish its dual-GPU card to ideal, but it preferred to abandon the GeForce 7950 GX2 in favor of the new G80 core and the GeForce 8800 series of graphics cards, which not only had higher performance but also a more advanced unified architecture.

As opposed to Nvidia in 2006, the former ATI Technologies doesn’t have such an opportunity in 2008. The ATI Radeon HD 3870 X2 must work ideally to be successful on the market whatever its price. The new card is schematically similar to the Nvidia GeForce 7950 GX2 but uses CrossFire rather than SLI technology:

The common thing between the new card from ATI and Nvidia’s solution is the use of a PCI Express switch that allows for a direct communication between the GPUs. The switch installed on the card complies with the PCI Express 1.1 specs, so the data-transfer speed is 4GB/s in each direction, although the RV670 supports PCI Express 2.0 and a twice higher communication speed. On the other hand, the capabilities provided by the PCI Express 2.0 standard are yet not called for by real applications, providing no performance boost, just like it was with AGP 8x.

One of the CrossFire channels is used for communication between the Master and Slave GPUs. The other is attached to the standard connector for the graphics card to support CrossFireX Quad configurations. Ironically, such a configuration is going to be much alike to the notorious Nvidia Quad SLI platform. Well, it may have a better fate because ATI’s multi-GPU support is implemented better than Nvidia’s, at least at the current moment.

The two GPUs of the ATI Radeon HD 3870 X2 card operate in the same way as two Radeon HD 3870 cards united in a CrossFire tandem.

The ATI Radeon X800 and X1000 used to support different multi-GPU modes, each with its own highs and lows:

Currently, the ATI Radeon HD 2000/3000 series do not support multi-GPU modes other than Alternate Frame Rendering although the ATI Radeon X1000 series used to work in Scissor and SuperTiling modes by default and enabled AFR only if the game profile was available in the driver.

Besides, Super AA modes are supported still. As opposed to the other CrossFire modes, these are intended to improve not performance but image quality by introducing additional FSAA modes (8x, 10x, 12x and 14x).

When you enable 8x or 12x FSAA, each GPU in the CrossFire pair works in 4x or 6x FSAA mode, respectively, but the samples are taken from different parts of the image and the frames are then combined into one to achieve FSAA equivalent to 8x or 12x. The 10x and 14x FSAA modes are a mix of traditional 4x/6x multisampling with additional antialiasing equivalent to 2x super-sampling. The number of texture samples in Super AA mode is doubled, which allows using 32x anisotropic filtering. Super AA modes are available in Direct3D as well as OpenGL applications.

We don’t know the reason for the changes in the CrossFire modes and if the SuperTiling and Scissor modes are going to be supported in the future but CrossFire technology may now prove to be even more dependent on the driver. There can also be the notorious AFR lags when one GPU outputs a frame that does not agree with the gamer’s actions one or two frames before.

Theoretically, AFR mode is the best one in terms of scalability because each GPU processes one frame, which eliminates the need to duplicate data, for example geometrical data. There is one thing that makes the whole picture not so bright, though. Besides the mentioned lags, data must be exchanged actively between the graphics core and the driver when the rendering of one frame depends on the results of the rendering of the previous frame. This is usually avoided by introducing an appropriate profile into the driver so that AFR could be effective. But if there is no such profile, the GPU array, or the ATI Radeon HD 3870 X2, switches into single-GPU mode with the appropriate performance loss. That’s not what you want from a new and expensive graphics card, of course.

So, the success of the ATI Radeon HD 3870 X2, and any other multi-GPU card such as Nvidia GeForce 7950 GX2, Nvidia GeForce 9800 GX2 and S3 Graphics ChromeMulti, depends largely on the programmers who are writing AFR profiles for as many games as possible.

Our tests will show how AFR is supported currently for the new graphics card. The next section is about the hardware of the Radeon HD 3870 X2.

Closer Look at ATI Radeon HD 3870 X2

PCB Design and Specifications

When two GPUs are installed on one graphics card, the wiring of an appropriate PCB proves to be a daunting task. The engineering folk from the former ATI Technologies have coped with the job brilliantly, fitting an advanced power circuit, both graphics cores, a switch chip, and two sets of memory chips into one PCB the size of an Nvidia GeForce 8800 GTX.

The ATI Radeon HD 3870 X2 seems to be longer, yet it is just an illusion provoked by the long casing of the cooler. The two graphics cards have the same dimensions with a length of 27 centimeters. Thus, the ATI Radeon HD 3870 X2 is one of the longest consumer-class graphics cards and may not fit into some system cases.

The cooler hides the most interesting parts of the card, so we had to take it off to scrutinize our sample of Radeon HD 3870 X2. An odd thing about the PCB is not that it is very complex and carries a lot of components, but that it is not populated uniformly. The back of the PCB is almost empty on both sides. It doesn’t seem to be reserved for further reinforcement of the power circuit as there are no seats for additional load-bearing elements here. Instead, there are a seat for some controller and seats for connectors. We don’t know what this part of the PCB was meant for, but its emptiness indicates at least a theoretical possibility that the ATI Radeon HD 3870 X2 could be made shorter with no loss in functionality.

The high component density made the developer use a more expensive digital power circuit working at a higher frequency but not requiring large electrolytic capacitors. Such a circuit was first deployed on ATI’s Radeon X1950 Pro and we can see the familiar elements here: the power supply of each GPU is managed by a dual-phase circuit with a Volterra VT1165MF controller. Each circuit can be reinforced by increasing the number of phases to three for the left GPU and four for the right GPU. There is a dedicated voltage regulator for each set of memory chips.

We know that the reference Radeon HD 3870 consumes up to 80W of power. Considering that the GPUs of the Radeon HD 3870 X2 are clocked at a higher frequency, the total peak power draw of the new card should be 170-180W. That’s why it is equipped with two power connectors. One of these connectors is an 8-pin PCI Express 2.0 one, with a load capacity of 150W. The card works well even if you use two 6-pin PCI Express 1.0 plugs. Like with the Radeon HD 2900, the plugging of a 6-pin cable into the card’s 8-pin connector only makes it impossible to overclock the card with the standard options of Catalyst. The connectors are placed somewhat inconveniently, far from each other and facing downward. It may be difficult to connect the power cables if the card is already installed in the system case.

A PEX8547 chip from PLX Technology is the card’s PCI Express switch. It has three PCI Express x16 ports complying with the PCI Express 1.1 specification, so the new card doesn’t support PCI Express 2.0 mode. This chip was developed specifically for high-performance graphics hardware. It features low latencies and Peer-to-Peer mode in which the graphics cores can communicate with each other directly, bypassing the controller. It’s similar to AMD’s 580X and 790 North Bridges.

Coming in PBGA packaging, the switch is rather large. It occupies more room on the card than the chip that used to be installed on the GeForce 7950 GX2. The PEX8547 has a power draw of 5W.

Two RV670 chips are placed closely to the right and left of the switch. There is nothing extraordinary about them except that their frequency is increased from 775MHz (the GPU frequency of the Radeon HD 3870) to 825MHz. It is a rather vague parameter, by the way, since ATI’s Radeon HD processors have 26 different frequency zones. The chips do not have protective frames around the dies. Theoretically, the Radeon HD 3870 X2 has got such tremendous resources as to challenge the Nvidia GeForce 8800 Ultra even. The new card features a total of 640 ALUs grouped into 128 computing units with 5 ALUs in each. It also has eight large texture processors and eight rasterization processors (ATI calls them render back-ends).

The texture processors and render back-ends have a complex architecture that was described in our reviews of the ATI Radeon HD 2900 XT and ATI Radeon HD 3800. Still, the ATI Radeon HD 3870 X2 can be said to have roughly 32 TMUs and 32 ROPs in the traditional terms. While the amount of ROPs is not a critical parameter in modern applications, the small number of TMUs has always been a bottleneck of the ATI Radeon HD architecture. The Radeon HD 3870 X2 is the first solution from AMD/ATI to be free from it.

The pure computing power the Radeon HD 3870 X2 can provide on MADD operations (Multiply-Add) is estimated by the developer at over 1 teraflop. That’s an impressive number but the Radeon HD architecture depends heavily on the shader code compiler. Added to that, the new card also depends on the efficiency of CrossFire technology. Like single RV670-based graphics cards, the ATI Radeon HD 3870 X2 supports PowerPlay, the power management technology from ATI.

As opposed to the Radeon HD 3870, the Radeon HD 3870 X2 uses cheaper GDDR3 memory. Each graphics core is surrounded with eight Samsung K4J52324QE-BJ1A chips, four on the face side of the PCB and four on the reverse side of it. These 512Mb chips (16Mb x 32) have a voltage of 1.9V for all the circuitry and a rated frequency of 1000 (2000) MHz. They are clocked at 900 (1800) MHz on the Radeon HD 3870 X2. The dense component mounting must have made it impossible to place the memory chips in the most optimal way and their frequency was reduced a little to ensure stable operation. The card features a total of 1024MB of memory, but only 512MB are available for 3D applications as is the case with every dual-GPU system.

The reference version of Radeon HD 3870 X2 is equipped with two dual-link DVI-I ports with support for the audio-over-HDMI feature. It also has a standard 7-pin mini-DIN connector for analog video output in Composite, S-Video and YPbPr formats. The single difference from the single-chip Radeon HD 3800 is that the card has only one CrossFire connector because the second channel is used by the card itself for its GPUs to communicate with one another. It means that CrossFire configurations with more than two Radeon HD 3870 X2 cards (and four Radeon HD 3800 GPUs) are unlikely to be supported.

Cooling System

Developing a cooler for a dual-chip graphics card is quite a problem but it was solved easily for the Radeon HD 3870 X2. In fact, this cooler consists of two coolers of the Radeon HD 3870 with the addition of a more powerful fan.

There are two individual heatsinks, one for each GPU. The chip that is closer to the fan is cooled with an aluminum heatsink. The more distant chip has a copper heatsink. The Radeon HD 3870 uses a copper heatsink actually, while the GPU frequency of the Radeon HD 3870 X2 is higher and it generates more heat. We guess the developer installed an aluminum heatsink to reduce the overall weight of the card. Each heatsink has a jut at the spot where it has contact with the GPU die. Traditional dark-gray thermal grease ensures proper thermal contact. The heatsinks are not mechanically connected with the base and are fastened to the PCB directly by means of four screws and a spring-loaded back-plate.

The other elements are cooled with the massive red-painted aluminum base. It also carries a fan and a casing made from red translucent plastic. Part of the base is something like a needle heatsink. Two types of thermal pads are used to ensure thermal contact with the memory chips, PCI Express switch and the load-bearing elements of the power circuit: elastic “sandwiches” with a layer of thermal grease between two pink pads, and pads that resemble the ones Nvidia uses on its cards. The cooler’s base is fastened to the PCB with 8 screws separately from the heatsinks. The memory chips on the reverse side of the PCB are cooled with an individual aluminum plate.

This cooling system should cope with its job quite well considering the relatively low heat dissipation of the RV670 chip, yet we’ve got some apprehensions concerning the GPU which is farther from the fan. As for the noise characteristics, you’ll learn them in the next section.

Noise, Temperature, Overclockability and Compatibility

We measured the level of noise produced by the ATI Radeon HD 3870 X2 with a digital sound-level meter Velleman DVM1326 using A-curve weighing. The level of ambient noise in our lab was 36dBA and the level of noise at a distance of 1 meter from the working testbed with a passively cooled graphics card inside was 43dBA. Here are the results:

The new card features an unusual method of controlling the speed of the cooler’s fan. The speed depends not only on the data from the thermode but also on the load on the command processors. As a result, the fan speed is being varied constantly and in a rather wide range under load, and the level of noise changes accordingly. The card is almost silent in 2D mode. It was hard but we tried to find the peak of noise, too. Most of it is produced by the air flowing through the heatsinks, which is perceived as quiet hiss. It is barely audible in a closed system case and is not irritating at all.

The Radeon HD 3870 X2 has two graphics cores but the appropriate screen of the Catalyst Control Center displays the temperature of the first core only. It varies from 51 to 56°C in idle mode and grows up to 78°C in 3D applications. The temperature of the second core should not differ more than 2-3°C from it. So the cooler copes with its job notwithstanding its simple design. As opposed to the Radeon HD 2900 XT whose power draw is comparable to the new card’s, the developer has managed to find the balance between cooling performance and comfortable noise characteristics thanks to the use of two rather economical GPUs.

We made an attempt to overclock our Radeon HD 3870 X2 using the standard options of the Catalyst Control Center, but it failed completely. The graphics card was not stable even if we increased the GPU frequency from 825 to 850MHz: there was a failure after a while and the driver would enable the restore mode. We left the serial card at that, but we are planning to volt-mod a Radeon HD 3870 X2 in the future to see what it can do at increased GPU and memory voltages.

The ATI Radeon HD 3870 X2 proved to be perfectly compatible with all mainboards we started it on. The card communicates with the bus via a PCI Express switch, and versions 1.1 and 1.0a of this interface have identical speed characteristics. That’s why there should not be any compatibility issues.

Testbed and Methods

To test the performance of ATI Radeon HD 3870 X2 in games we assembled the following test platform:

According to our testing methodology, the drivers were set up to provide the highest possible quality of texture filtering and to minimize the effect of software optimizations used by default by both: AMD/ATI and Nvidia. Also, to ensure maximum image quality, we enabled transparent texture filtering - Adaptive Anti-Aliasing/Multi-sampling for ATI Catalyst and Antialiasing – Transparency: Multisampling for Nvidia ForceWare. As a result, our ATI and Nvidia driver settings looked as follows:

ATI Catalyst:

Nvidia ForceWare:

For our tests we used the following games and benchmarks:

First-Person 3D Shooters

Third-Person 3D Shooters

RPG

Strategies

Synthetic Benchmarks

We selected the highest possible level of detail in each game using standard tools provided by the game itself from the gaming menu. The games configuration files weren’t modified in any way. The only exception was Enemy Territory: Quake Wars game where we disabled the built-in fps rate limitation locked at 30fps.

Games supporting DirectX 10 were tested in this particular mode. With a few exceptions, the tests were performed in the following most widely spread resolutions: 1280x1024/960, 1600x1200 and 1920x1200. If the game didn’t support 16:10 display format, we set the last resolution to 1920x1440. We decided to postpone testing in 2560x1600 until we upgrade our testbeds accordingly and complete the article on ATI CrossFireX and Nvidia Triple SLI multi-processor solutions.

We used “eye candy” mode everywhere, where it was possible without disabling the HDR/Shader Model 3.0/Shader Model 4.0. Namely, we ran the tests with enabled anisotropic filtering 16x as well as MSAA 4x antialiasing. We enabled them from the game’s menu. If this was not possible, we forced them using the appropriate driver settings of ATI Catalyst and Nvidia ForceWare drivers

Performance was measured with the games’ own tools and the original demos were recorded if possible. Otherwise, the performance was measured manually with Fraps utility version 2.9.1. We measured not only the average speed, but also the minimum speed of the cards where possible.

ATI Radeon HD 3870 X2 will be competing against the following graphics accelerators participating in our test session:

Performance in First-Person 3D Shooters

Battlefield 2142

This game doesn’t support display resolutions of 16:10 format, so we use a resolution of 1920x1440 pixels (4:3 format) instead of 1920x1200 for it.

It is neither a triumph nor a failure for the new card. The Radeon HD 3870 X2 copes with the load successfully being almost as fast as the GeForce 8800 GTX and 8800 GTS 512MB in terms of average performance. It delivers a somewhat lower minimum speed, probably due to the specifics of CrossFire technology, yet this speed is never lower than 40fps which is quite a comfortable level.

BioShock

BioShock doesn’t support FSAA when running in Windows Vista’s DirectX 10 environment. That’s why we benchmarked the cards without FSAA.

Radeon HD 3870 X2 performs brilliantly in this one of the most beautiful games of 2007. Nvidia GeForce 8800 GTS 512MB suffered a dramatic defeat here. Its victory is especially impressive in 1920x1200, where the new ATI solution managed to get more than 50% ahead of the competitor. Excellent result proving everything we have said about the impressive potential of the two RV670 chips tandem.

Call of Juarez

The ATI Radeon HD 3870 X2 has the best average result at 1600x1200 and higher, but its minimum speed is considerably lower than that of the Nvidia GeForce 8800 GTX and even of the single Radeon HD 3870. Perhaps it is due to some flaws in the software on which the new graphics card depends just like any other multi-GPU solution.

Well, the GeForce 8800 GTX cannot provide a comfortable speed, either, even at 1280x1024 if you use the highest graphics quality settings together with FSAA. So the results have little practical value.

Call of Duty 4: Modern Warfare

CrossFire technology doesn’t work right here: the Radeon HD 3870 X2 is somewhat slower than the single ATI Radeon HD 3870. That’s not a good thing as the new card is positioned by its developer as an opponent to Nvidia’s fastest single-chip solutions. We hope this problem will be corrected in the next version of Catalyst.

Crysis

The game being too hard at its Very High level of detail, we benchmarked the cards without FSAA to get a more playable speed.

Like in Call of Juarez, the ATI Radeon HD 3870 X2 has good results, especially at high resolutions. It would be the leader if it were not for its low minimum of speed. Moreover, even two RV670 cores prove to be not enough to ensure a comfortable average frame rate. This game is too hard at its maximum graphics quality settings.

Enemy Territory: Quake Wars

The frame rate is fixed at 30fps in this game as this is the rate at which the physical model is being updated at the server. Thus, this 30fps speed is the required minimum for playing the game.

It looks like ATI solutions’ dislike of OpenGL applications is still here. The Radeon HD 3870 X2 is as fast as the single Radeon HD 3870, which means that only one of its cores is functioning although CrossFire mode cannot be disabled on the reference Radeon HD 3870 X2. That’s not a complete failure since 35fps is quite an acceptable average speed for this game, yet the gamer may ask for more from a $449 card. Hopefully, this problem will be corrected with driver updates.

Half-Life 2: Episode Two

The ATI Radeon HD 3870 X2 is confidently ahead of the Nvidia GeForce 8800 GTS 512MB: by 10% at low resolutions and by 15-17% at high resolutions. The new card yields an average frame rate of near 60fps even at 1920x1200. That’s just what we should expect from a $449 product.

S.T.A.L.K.E.R.: Shadow of Chernobyl

The game doesn’t support FSAA when you enable the dynamic lighting model, but loses much of its visual appeal with the static model. This is the reason why we benchmarked the cards in S.T.A.L.K.E.R. using anisotropic filtering only.

ATI Radeon HD graphics cards have had problems in this test since their very release. The Radeon HD 3870 X2 puts an end to this as it is competitive against the GeForce 8800 GTS 512MB. That’s not a victory since the ATI card is more expensive and is slower than the GeForce 8800 GTS/Ultra, yet it makes the resolution of 1920x1200 playable.

Note that the Radeon HD 3870 X2 is about two times as fast as the single Radeon HD 3870. This is explained by the higher frequencies of the former card’s GPUs.

Unreal Tournament 3

Forcing FSAA from the graphics card’s driver doesn’t produce any effect as yet. That’s why the game is tested with anisotropic filtering only.

The ATI Radeon HD 3870 X2 is just as fast as Nvidia’s single-core cards GeForce 8800 GTX and GeForce 8800 GTS 512MB. They all reach the highest speed possible on our testbed at resolutions below 1920x1200. UT3 doesn’t suit well to reveal the scalability of a CrossFire system as it is perfectly optimized and runs very fast even on the single Radeon HD 3870.

Performance in Third-Person 3D Shooters

Lost Planet: Extreme Condition

CrossFire doesn’t work right here. The Radeon HD 3870 X2 is terribly slow even in comparison with the single Radeon HD 3870. Hopefully, this is not a fundamental problem related to the specifics of the game engine with its rendering techniques. If so, it is likely to be solved in the next version of the Catalyst driver.

Tomb Raider: Legend

Everything we said about Lost Planet is true here, too. We hope ATI’s programmers are already working on the driver.

Performance in RPG

Hellgate: London

Alas, there are problems with CrossFire in this game, too. There is no or little performance gain relative to the single card, which indicates the use of only one graphics core. Moreover, the minimum speed plummets at high resolutions.

Gothic 3

The current version of the game doesn’t support FSAA, so we performed the test with anisotropic filtering only.

The dual-chip Radeon HD 3870 X2 is again slower than the single-chip Radeon HD 3870 in terms of average frame rate, even though slightly. The minimum speed is considerably lower, however, which is indicative of certain flaws in the current version of the Catalyst driver.

The Elder Scrolls IV: Oblivion

The game loses much of its visual appeal without HDR. Although some gamers argue that point, we think TES IV looks best with enabled FP HDR and test it in this mode.

Breaking no records, the new card still looks good against the GeForce 8800 GTX and even takes the lead at 1920x1200. It differs from Nvidia’s solutions in having a lower minimum of speed, but this is no problem for the gamer as it is never lower than 42fps.

In open scenes the Radeon HD 3870 X2 is quite competitive, too. Although CrossFire technology is far from its maximum efficiency here, the new card easily delivers comfortable speed being inferior only to the GeForce 8800 GTX at 1920x1200.

Performance in Realtime Strategy Games

Company of Heroes: Opposing Fronts

The new add-on to Company of Heroes is tested in DirectX 10 mode only since it provides the highest level of detail and hence the highest quality of the visuals, which guarantees the best gaming experience.

According to the obtained results, the second GPU of ATI Radeon HD 3870 X2 was not involved. Besides, we once again see the drop of minimal fps rate. So, we cannot recommend this graphics card for the Company of Heroes fans.

Command & Conquer 3: Tiberium Wars

Since the game has frame rate limitation, you should consider the minimum speed of the cards in the first place.

Because of the average frame rate limitation, it is impossible to single out a performance leader among the today’s fastest single graphics cards, at least not without testing in extremely high resolutions. All testing participants, including ATI Radeon HD 3870 X2 work just fine in standard resolutions with enabled FSAA 4x.

World in Conflict

CrossFire mode doesn’t work properly here, which leads to significant performance drop compared with a single ATI Radeon HD 3870. Unfortunately, as of today we can’t say that ATI Radeon HD 3870 X2 will be a good choice for all the gamers.

Performance in Synthetic Benchmarks

Futuremark 3DMark05

At a resolution of 1024x768 without FSAA the ATI Radeon HD 3870 X2 can’t show its worth, and its advantage over the other cards is small. Anyway, the new card overcomes the 18,000 barrier.

The ATI Radeon HD 3870 X2 is hardly better than the single-chip cards in the first test because the speed of this test depends largely on the card’s texture-processing performance. The new card’s texturing capabilities are roughly similar to those of the GeForce 8800 GTX and GTS 512MB. Each of these cards has 32 TMUs.

The dual-chip solution from AMD shows its best in the second test that requires high shader-processing performance. The Radeon HD 3870 X2 with its total of 640 ALUs is currently unrivalled when it comes to sheer computing power.

The third test is an in-between situation. The ATI Radeon HD 3870 X2 is in the lead, but doesn’t enjoy such a huge advantage as in the second test. The explanation is obvious: this test demands both high shader-processing performance and high texturing speed. Comparing the numbers we see in the individual tests with the total scores, the ATI Radeon HD 3870 X2 feels best at high resolutions as well as in those applications whose overall performance is not limited by the speed of the texture processors.

Futuremark 3DMark06

3DMark06 makes good use of the resources provided by the Radeon HD 3870 X2 right away, and the new graphics card leaves its opponents, including the GeForce 8800 GTX, far behind. The overall score of over 13,000 is obviously a record for a serial single graphics card working at its default frequencies.

As you could expect, the ATI Radeon HD 3870 X2 has the biggest lead over the other cards in the SM3.0/HDR tests where it is 35% ahead of the GeForce 8800 GTS 512MB. Its results are not that impressive in the SM2.0 group and it probably wins due to the second test. Let’s see if this supposition is correct.

Yes, the Radeon HD 3870 X2 is slightly behind the Nvidia GeForce 8800 GTS 512MB in the first test, which represents a more complex version of the first gaming test from 3DMark05. But in the second test the new card goes ahead just like it did in 3DMark05.

The ATI Radeon HD 3870 X2 is unrivalled in the SM3.0/HDR tests that abound in pixel shaders. It is 57% and 60% ahead of the fastest single-chip card in the first and second test, respectively. That’s quite predictable as the Radeon HD 3870 X2 has as many TMUs as Nvidia’s solutions but is far superior in computing power. So, it loses slightly in one test and triumphs in the other three. This agrees with the overall scores.

Conclusion

It’s time to come to a conclusion about the new graphics card from AMD, ATI Radeon HD 3870 X2, but our tests produce a rather ambiguous picture.

The new card is a technical success. The developer had managed to accommodate two RV670 chips with all the accompanying components, including memory chips and voltage regulators, together with a rather large PCI Express switch on one PCB and remain within the dimensions of a GeForce 8800 GTX/Ultra. The RV670 doesn’t generate much heat and supports PowerPlay technology – this allows the card to do along with a simple cooler without heat pipes which have become a typical attribute of top-performance graphics cards. But what about performance in real 3D applications, the first and foremost characteristic of every graphics card?

On one hand, the developer has indeed created a top-end single-PCB graphics card capable of challenging Nvidia’s GeForce 8800 GTX/Ultra and 8800 GTS 512MB and even beating them in some cases. This is confirmed by our tests in a number of popular games including such titles as BioShock and Half-Life 2: Episode Two. Both versions of Futuremark 3DMark we benchmarked the new card in testified to its huge potential, worthy of a new king of the 3D realm. Unfortunately, we cannot yet crown it because CrossFire technology is not 100% correct, at least at the moment of the announcement.

The new card won six out of the nineteen tests, at least at high resolutions, and in five more was comparable to Nvidia’s top-end single-chip solutions. This indicates its big potential.

On the other hand, it was either equal to or slower than the single-chip ATI Radeon HD 3870 in seven out of the nineteen tests, namely in Call of Duty 4, Enemy Territory: Quake Wars, Lost Planet: Extreme Condition, Tomb Raider: Legend, Hellgate: London, Gothic 3 and Company of Heroes: Opposing Fronts. So, in some of these games only one of the new card’s GPUs was employed, and in others CrossFire technology didn’t work altogether.

It is too early yet to call the Radeon HD 3870 X2 a success or a defeat. A gamer who buys a $449 graphics card touted as a flagship product with unrivalled performance expects it to provide maximum performance in all, or nearly all, of his favorite games, which means ATI still has a lot of work to do until the new card becomes a true king of 3D. If you have already got an interest in the Radeon HD 3870 X2, you may want to make sure it is compatible with the games you play that are not included into this review.

The long-term perspective of the ATI Radeon HD 3870 X2 is rather vague yet because we don’t know about the level of performance of the upcoming opponents as well as about their support for quad-GPU configurations.

Highs:

Lows: