ATI Radeon HD 4870 X2 Graphics Accelerator: New Champion

We have long waited for the new dual-GPU ATI graphics cards to come out and finally it happened. Our today’s article should at last determine what strategy turned out more efficient: multi-GPU concept supported by ATI/AMD or a single-GPU concept chosen by Nvidia.

by Alexey Stepin , Yaroslav Lyssenko
08/22/2008 | 05:02 PM

Multi-GPU technologies that allow to combine a few GPUs into a single top-performance graphics subsystem have never been truly recognized and accepted by the user community. Historically, no such technology had ever really taken off, from antediluvian artifacts such as 3dfx Voodoo2 SLI and ATI Rage MAXX to recent solutions from ATI and Nvidia. At some point you could get certain performance benefits by using such technologies (often accompanied with all manner of technical and software problems, though) but the next generation of GPUs would always be faster than a multi-processor system built out of previous-generation GPUs.

 

But as it transpired recently, the system requirements of modern game engines had been growing far faster than the capabilities of monolithic graphics cores that might be able to meet those requirements. The release of the Radeon HD 3870 X2 was the first sign of the changing situation even though that graphics card was introduced only because ATI didn’t have competitive premium-class GPUs then. The dual-processor card performed well in 3D applications and indicated ATI’s new approach to building top-performance premium-class solutions. Ironically, it was the lack of a fast monolithic core that helped ATI to see its future strategy. In our review of the Radeon HD 3870 X2 we wrote that ATI’s introduction of the multi-GPU graphics card was just a tactical decision. It was kind of forced on the company. But it actually marked the beginning of a new era.

Nvidia also introduced a dual-processor premium-class solution of its own making but the GeForce 9800 GX2 was not much of a success. The graphics card suffered from all manner of typical problems while the developer abandoned it and focused again on creating yet another monolithic monster chip. And they did create it. But soon after the announcement of ATI’s new solutions it turned out that the G200 chip, notwithstanding its huge size, tremendous complexity and high power consumption, was not overwhelmingly better than the simpler RV770. It could even be slower in some situations! Nvidia even had to cut the prices on GeForce GTX 200 series products to make them competitive.

AMD’s graphics department, the former ATI Technologies, was calm, relying on its new strategy. The company’s $199 and $299 solutions delivered superb performance and enjoyed deserved popularity. And ATI was ready to strike the final blow and dethrone Nvidia completely by introducing a new generation of Radeon HD X2. The announcement of this product was delayed to August 12, although the RV770 chip had been introduced on June 25. They were in no hurry just because Nvidia had nothing to respond with. ATI put all that time to good use in order to polish off its new generation of dual-processor graphics card to perfection. Now it’s time for us to check out the results.

The Radeon HD 4870 X2 is originally targeted at the over-$500 segment. To avoid a gap in the product line-up, the less expensive Radeon HD 4850 X2 is released into the below-$400 sector.

Thus, ATI covered every price range from $199 to $549 and challenged Nvidia where the latter had been superior. We will see if AMD can win the battle in this review. Welcome the ATI Radeon HD 4870 X2!

ATI Radeon HD 4870 X2: Specifications and Innovations

Conceptually, ATI’s new attempt to create the world’s fastest graphics card differs but slightly from the Radeon HD 3870 X2. It just employs new-generation RV770 cores instead of RV670 and GDDR5 memory instead of GDDR3. It has the following specifications (in comparison with its opponent and predecessor):

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You can see that both dual-RV770 cards are equipped with 2 gigabytes of onboard memory, which is more than the Radeon HD 3870 X2 had. For technical reasons, applications can make use of only 1 gigabyte of this memory, as you know. So, these cards are equal to the GeForce GTX 280 in this respect or even slightly better considering the more efficient memory management of ATI’s solutions. The Radeon HD 4800 X2 cards are going to show their best in new-generation games and/or at extreme resolutions (above 1920x1200 pixels). We will check this supposition out in our tests soon. The senior model has a total memory bandwidth of over 200GBps. The junior model’s 128GBps bandwidth is lower than that of the GeForce GTX 280, but quite high anyway.

The sheer amount of the new cards’ computing resources is astounding as they have as many as 1600 ALUs. ATI claims the senior model of the new series can perform at 2.4 teraflops which is an industry record. The Radeon HD 4870 X2 are going to be only about half that fast at double-precision computations, but this is far faster than what the GeForce GTX 280 can do anyway. As concerns texture mapping and rasterization/antialiasing, the Radeon HD 4800 X2 are equal to Nvidia’s flagship solution, but the latter’s texture processors are less effective in practice and we can expect the new cards to be better from this aspect, too.

The above-mentioned innovations are interesting, yet not really innovative. The cards are just equipped with more resources than before. But there are some truly new features about the new Radeon HD 4800 X2. First, it is the interface type. The previous generation of ATI’s dual-processor cards supported PCI Express 1.1 whereas the new series is endowed with PCI Express 2.0 thanks to a second-generation PCI Express switch. The communication channel between the two GPUs is thus twice as wider as before (5GBps rather than 2.5GBps in each direction) which is important since many rendering techniques employed in modern games require data transfers between the GPUs in a multi-GPU subsystem.

The Radeon HD 4800 X2 also have something the Radeon HD 3870 X2 had not. We mean an additional data-transfer channel called Sideport. This is a direct link between the two GPUs that provide an additional bandwidth of 5GBps in each direction. Thus, the total theoretical bandwidth of the internal interfaces of the Radeon HD 4800 X2 cards is as high as 21.8GBps which eliminates any possibility of a bottleneck and improves the overall scalability of CrossFireX technology. This additional data-transfer channel can hardly be called for in modern games, though. This must be the reason why the Sideport interface is currently disabled on the software level.

At the moment of its announcement the new graphics card series includes two models of Radeon HD 4800 X2 differing in clock rates and memory type. They come at a recommended price of $549 for the senior model and $399 for the junior model. We’ve got a sample of the senior version of the card equipped with GDDR5 memory. It is the more interesting of the two because the Radeon HD 4870 X2 is the solution that must beat Nvidia’s GeForce GTX 280. ATI’s fans pin their hopes on it. Our sample is manufactured by Tul Corporation, the supplier of graphics cards under the PowerColor brand. Let’s check out the packaging and accessories of this product first.

PowerColor HD 4870X2 2GB GDDR5: Package and Accessories

The PowerColor HD 4870X2 2GB GDDR5 graphics card (the AX4870X2 2GBD5-H model; we’ll call it just PowerColor HD 4870 X2 hereafter) comes in a medium-sized box, even though it is a top-end solution. Well, the supplier pays less for storage and the buyer will pay less for the card. It sounds fair enough. There is nothing extraordinary about the exterior design of the box. There is a picture of yet another girl (or is it a boy?) with a sword on the face side of it. Graphics card makers are so fond of such pictures and use them so abundantly that those girls or boys just fail to attract any user attention anymore.

The package is quite informational but there is one tricky caption. The card is said to offer 2 gigabyte of graphics memory which is not actually true with regards to homogeneous multi-GPU solutions like the Radeon HD 4870 X2. 3D applications can use only half the total amount of memory or 1 gigabyte in this case. That’s not a problem since Nvidia’s flagship product GeForce GTX 280 comes with 1 gigabyte of graphics memory, too. It is a normal amount of memory for a modern graphics card that is positioned in the premium class.

The graphics card and its accessories lie in the cardboard compartments of the box. We found the following things in there:

The accessories are rather odd for a $549 product as well as for the year of 2008. There are two rather unnecessary adapters for analog video connections, for example. While YPbPr ensures an acceptable image quality, the Composite format is now obsolete and is hardly used by modern display devices. Instead, we’d like to have a power adapter (2x6-pin PCI Express → 1x8-pin PCI Express) because not all modern PSUs that may be used together with the Radeon HD 4870 X2 are equipped with 8-pin connectors for graphics cards. For example, the Enermax Liberty ELT620AWT power supply, a good but not new model, doesn’t have such connectors.

There is also no software for playing HD video that would match the capabilities of ATI’s UVD 2 video-processor. Such software may cost you $50 and more if purchased separately while its OEM version for graphics card makers would be cheaper and wouldn’t affect the cost of the product much. We guess a HD video player must be included with $500 graphics cards. People who shell out such a nice sum of money should be able to use every feature of the product they purchase without any additional investment.

Overall, the packaging of the PowerColor HD 4870 X2 gives us no real cause for being critical. Although without any originality in design, it is not too big and easily fits into a plastic bag. The accessories might have been better, though. We are especially disappointed at the lack of a software player that would support HD video and the hardware capabilities of ATI’s GPUs in video decoding and processing. The lack of a power adapter for an 8-pin PCI Express connector is not good, either.

ATI Radeon HD 4870 X2: PCB Design

The Radeon HD 4870 X2 graphics card is a very sophisticated thing as it has to carry two GPUs with accompanying memory chips and power systems. A PCI Express switch must also be accommodated on the PCB. Designing such a graphics card is a daunting task but ATI’s engineers drew upon their earlier experience with the Radeon HD 3870 X2 and solved the problem brilliantly. Although the new card carries two RV770 cores, it is no larger than the single-processor GeForce GTX 280. Both are 27 centimeters long.

 

Of course, 27 centimeters is quite a lot. The new card won’t fit into all system cases. On the other hand, such top-performance solutions are not meant for compact cases actually. The Radeon HD 4870 X2 doesn’t look as massive as the GeForce GTX 280 because it doesn’t have a metallic casing as the latter. Interestingly, ATI’s dual-processor flagship is painted black rather than the company’s traditional red. This must have been done to make it look more impressive, an indication that this card belongs to the elite of the 3D hardware world.

As opposed to the GeForce GTX 280, the cooler of the Radeon HD 4870 X2 can be removed easily, giving you the access to the exciting internals of the new card. The overall component layout resembles the Radeon HD 3870 X2. The new card is in fact the result of the evolution of the latter.

Although the back part of the PCB is still empty, the power circuit has been revised and reinforced because the RV770 chip needs more power than the RV670. It incorporates two three-phase voltage regulators based on Volterra VT1165MF controllers that can often be seen in high-frequency voltage regulators of modern graphics cards. Each set of memory chips is powered by a separate regulator. As opposed to the 3870 X2, there is no place to reinforce the power circuit further.

The single Radeon HD 4870 is known to have a peak power consumption of 130 watts. So, the Radeon HD 4870 X2, which in fact combines two such cards on one PCB, should require two times as much, i.e. 260 watts. Therefore the 8-pin PCI Express 2.0 connector is a must. A high load is expected on this connector because the Radeon HD 4870 X2 won’t even start up, reporting power problems, unless you connect the appropriate PSU plug to it. The card can be made to work with two 6-pin power connectors but we wouldn’t recommend you to do that for the reasons explained below. The connectors are placed facing downward which makes it inconvenient to plug the power cables into the card when it is already installed into the system.

A PEX8647 chip from PLX Technology is responsible for data transfers between the two RV770 cores. It is a second-generation 3-port PCI Express switch supporting PCI Express 2.0 which means a double data-transfer rate. Like its predecessor PEX8547, the new switch supports peer-to-peer mode for direct data transfers between the GPUs, bypassing the root PCI Express controller in the mainboard’s chipset. Notwithstanding the improved specs, the new switch has a very low level of power consumption, only 3.8W, whereas its predecessor required about 5W at lower data-transfer rates. The new chip is also considerably smaller.

Besides using the switch, the GPUs can communicate via the CrossFire interface or the additional data-transfer channel called Sideport which provides a bandwidth of 5GBps in each direction (the Sideport is currently disabled on the software level). The Radeon HD 4870 X2 being in fact a mix of two Radeon HD 4870 cards, the GPUs are linked with a traditional CrossFire channel. There is also one CrossFire connector on the PCB to support quad-processor configurations. You can’t use more than two Radeon HD 4870 X2 cards in a single graphics subsystem due to technical reasons. And such a subsystem, if possible, would have tremendous power requirements!

The RV770 cores are placed on both sides of the switch. As opposed to the Radeon HD 3870 X2, the developer didn’t increase their clock rates relative to the single-chip card, obviously due to power consumption reasons. Thus, the GPUs are clocked at 750MHz like on the ordinary Radeon HD 4870. They have a standard configuration with 800 ALUs (grouped into 160 superscalar execution modules), 40 texture processors and 16 raster back-ends. The Radeon HD 4870 X2 thus has a total of 1600 ALUs, 80 texture processors and 32 raster back-ends. This should be enough to beat any single graphics card from Nvidia including the GeForce GTX 280 and GeForce 9800 GX2. Unlike the Radeon HD 3870 X2, the 4870 X2 doesn’t seem to have any theoretical bottlenecks. The only problem it may suffer from is the lack of CrossFire support in the drivers, but that’s the common problem of any modern homogeneous multi-GPU system from both ATI and Nvidia. In the worst case, the card will have only one of its GPUs working, but the RV770 is quite competitive to Nvidia’s G200-based solutions even alone.

The titanic computing capacity of the Radeon HD 4870 X2 is only one constituent of its expected triumph in games. The other constituent is the memory subsystem that should affect the card’s performance greatly in at high resolutions. The new card carries two sets of eight GDDR5 chips with a total capacity of 2 gigabytes, i.e. 1 gigabyte for each graphics core. The ordinary Radeon HD 4870 comes with Qimonda IDGV51-05A1F1C-40X chips. The dual-core Radeon HD 4870 X2 is equipped with Hynix H5GQ1H24MJR-T0C memory (1Gb chips, 32Mb x 32, 1.5V). The chips are rated for a frequency of 1000 (4000) MHz but are clocked at 900 (3600) MHz by the card. 3D applications can access 1 gigabyte of graphics memory since this is a homogeneous dual-processor solution. The Radeon HD 4870 X2 should not feel a lack of graphics memory especially as ATI’s solutions feature more efficient memory management than their Nvidia counterparts. The new card has a total memory bandwidth of 230.4GBps which is far higher than what Nvidia’s single graphics cards can offer. So, the Radeon HD 4870 X2 is an armed and dangerous rival to any opponent. It is virtually free from weaknesses.

The card has a standard configuration of connectors. It has two DVI-I ports with support for resolutions up to 2560x1600 pixels. Contrary to Nvidia’s SLI systems, the Radeon HD 4870 X2 provides full support for multi-monitor configurations. It also offers a universal 7-pin mini-DIN connector which is hardly necessary today, in the era of HDMI. As mentioned above, there is one CrossFire connector on the PCB so that you could use the card in a quad-GPU subsystem together with another Radeon HD 4870 X2.

ATI Radeon HD 4870 X2: Cooling System

Dissipating 170 watts of heat is a daunting task, considering all the restrictions concerning the design of a graphics card’s cooling system, but the Radeon HD 4870 X2 is expected to produce even more heat than its predecessor Radeon HD 3870 X2! So, we were very interested to see what cooler it came with.

Strangely enough, ATI didn’t take the problem seriously and didn’t introduce any great changes into the cooling system of the Radeon HD 4870 X2. It still consists of two solid heatsinks but, unlike on the Radeon HD 3870 X2, both are made from copper. Such heatsinks are rather effective as their ribs are a single whole with the base. As opposed to composite heatsinks, there is no additional thermal resistance where the ribs meet the sole. Still, it is rather odd that the cooler of a graphics card with a predicted power draw of 260W does not have any heat pipes (unless you count the thermal chamber on one of the heatsinks as such a pipe). There is a layer of classic dark-gray thermal grease between the GPU dies and the heatsinks.

This cooler design seems rather risky to us even if ATI achieved high efficiency by means of increasing the cooler’s fan speed (and noise). The heatsinks are fastened to the PCB with four screws and a spring-loaded back-plate. They are not connected firmly to the cooler’s frame but seem to give some heat to it anyway, which should increase the overall cooling performance a little more.

The cooler’s frame serves as a heat-spreader for the load-bearing components of the power circuit, for the memory chips located on the face side of the PCB, and for the PCI Express switch. It also serves as a seat for the fan. Elastic rubber-like pads are employed as a thermal interface. Their efficiency isn’t high, but the mentioned components do not produce as much heat as the GPUs. At the top of the frame there are a number of needle-shaped protrusions that increase its heat-spreading efficiency. The frame is fastened to the PCB with eight screws. The memory chips at the reverse side of the PCB are cooled with a separate aluminum plate.

The cooler uses the same fan as in the Radeon HD 4870’s cooler: it is the CF1275-B30H-C004 model from NTK Technologies. The peak consumption current of this fan is 1A. In other words, it can consume up to 12W at a voltage of 12V. The fan is powerful enough to cool even two heatsinks, the question is how noisy it will be while doing that.

The hot air is exhausted through the slits in the card’s mounting bracket. The card consuming some 260W, your computer may become an additional source of heat in winter. It won’t be so good in summer, though. The cooler’s casing is made from dark-brown translucent plastic. There is a sticker near the needle-shaped heatsink warning you of the high temperature of the latter.

So, the cooling system of the Radeon HD 4870 X2 is rather too simple for a graphics card with a predicted heat dissipation of 250-260W. We hope it does its job well without being a torture for your ears. We’ll check this out in the next section.

ATI Radeon HD 4870 X2: Power Consumption, Temperature, Noise, Compatibility

It’s going to be interesting to check out the power consumption of the Radeon HD 4870 X2 just because this is the first graphics card that will surely need more than 200 watts of juice. No single graphics card has ever had such a high power draw notwithstanding what the developers said. So, we measured the power consumption of the card on a special testbed configured like follows:

The 3D load was created by means of the first SM3.0/HDR test from 3DMark06 running in a loop at 1600x1200 with 4x FSAA and 16x AF. Practice suggests it is a heavier load for the graphics card than the tests of 3DMark Vantage. The Peak 2D mode was emulated by means of the 2D Transparent Windows test from PCMark05. This test is important as it simulates the user’s working with application windows whereas Windows Vista’s Aero interface uses 3D features. Perhaps we’ll replace it with a HD video playback test which should be more interesting for the end-user. Here are the results:


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So, the peak power consumption of the Radeon HD 4870 X2 is indeed as high as we predicted. It is the most voracious among all graphics cards we have ever tested. Its results in the 2D and Peak 2D modes are high, of course, yet do not differ much from those of the ordinary Radeon HD 4870. But the 3D result is terrific and far higher than everything we’ve seen before. This graphics card really needs a high-wattage power supply. It also needs an 8-pin PCI Express 2.0 power connector because it is this connector that carries the biggest load which nearly reaches the allowable maximum of 150W. Yes, you can make your Radeon HD 4870 X2 work with two 6-pin connectors but this experiment may prove disastrous because one connector will work under much higher load than what it is rated for.

Of course, the level of heat dissipation is as high as power consumption. RivaTuner doesn’t support the new card yet, but the Catalyst Control Center reported that the temperature of the GPUs on the Radeon HD 4870 X2 varied from 64°C in idle mode to 86-90°C under 3D load. The numbers seem to be acceptable but we don’t know for sure what exactly temperature the Control Center reports as the card has two GPUs and both contribute to the total amount of heat generated by the card. We know that the clock rate of the Master core is reduced to 500MHz in idle mode while the Slave core is either disabled or nearly disabled in this mode as is indicated by the power consumption tests. The warning sticker on the cooler’s casing tells you the truth, by the way. The card is indeed very hot. You can barely hold it in your hands after it has worked in 3D mode for a while.

Next we measured the amount of noise produced by the card using a Velleman DVM1326 noise-level meter. Here are the results:

Not very pleasant results these are. The card is not very noisy in 2D mode but the fan accelerates under load in order to cool the two heatsinks properly and the level of noise grows considerably, nearly reaching that of the Radeon HD 2900 XT’s cooler. Subjectively, the noise is not irritating. You can hear the sound of the airflow passing through the heatsinks rather than any noises from the fan, but the card has the same drawback as the single Radeon HD 4870. The fan speed management system is too smart. It is constantly adjusting the speed of the fan and the resulting variations in noise level may be rather irritating.

Despite the use of a PCI Express switch, the ATI Radeon HD 4870 X2 has no compatibility issues with different chipsets and mainboard whatever version (2.0, 1.0a or 1.1) of the PCI Express interface they support.

Testbed and Methods

For our performance tests of ATI Radeon HD 4870 X2 we put together the following testbed:

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. 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 synthetic 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, because the user doesn’t have to know how to do it. 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.

Besides ATI Radeon HD 4870 X2we have also included the following graphics accelerators to participate in our test session:

Besides, we have also tested ATI Radeon HD 4870 and ATI Radeon HD 4850 in CrossFire configurations.

Since ATI Radeon HD 4870 X2 belongs to the top price range, we expanded the standard set of resolutions with 2560x1600 and 2048x1536, the latter for those games that do not support 16:10 aspect ratio. 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 MSAA 4x antialiasing and anisotropic filtering 16x in all tests except 3DMark. 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.

Performance in First-Person 3D Shooters

Battlefield 2142

This game doesn’t support display resolutions of 16:10 format, so we use resolutions of 4:3 format instead.

The Radeon HD 4870 X2 finds this test to be just too easy. Even with the Sideport interface disabled, it has a higher bottom speed than the ordinary Radeon HD 4870 CrossFire configuration. This must be due to the PCI Express switch that allows the GPUs to communicate directly, bypassing the root PCI Express controller and avoiding the associated data transfer latencies.

BioShock

BioShock doesn’t support FSAA when running in Windows Vista’s DirectX 10 environment. We benchmark graphics cards without FSAA in this game.

Although the game runs on the relatively undemanding Unreal Engine 3 and does not use full-screen antialiasing, the Radeon HD 4870 X2 delivers superb performance, notching over 100fps at 2560x1600 and outpacing the GeForce GTX 280 by almost 75%. As opposed to the classic pair of CrossFire-linked Radeon HD 4870 cards the new Radeon is absolutely stable and has no CrossFire-related problems.

Call of Juarez

Call of Juarez does not support 2560x1600 resolution, so we have to limit our tests to 1920x1200.

The average frame rate of the Radeon HD 4870 X2 is lower than that of the Radeon HD 4870 CrossFire configuration but the bottom speed is almost the same. It means you can play the game comfortably at resolutions up to 1600x1200/1680x1050 pixels. Considering that Call of Juarez uses advanced rendering techniques, we can expect the Radeon HD 4870 X2 to be even faster after its Sideport interface is unlocked.

Call of Duty 4: Modern Warfare

The Radeon HD 4870 X2 has a higher bottom speed than the Radeon HD 4870 CrossFire, especially at 2560x1600 where its larger amount of graphics memory seems to be the crucial factor. The ATI solution is only 6% slower than the GeForce GTX 280 but this makes no difference. Both cards can be used to play the game at 2560x1600 with 4x MSAA.

Crysis

This game is tested at the High level of detail, excepting the Shaders option which is set at Very High. This way we try to achieve a compromise between image quality and speed.

Alas, there is no breakthrough which we had expected. The Sideport interface will hardly make it possible it, too. Anyway, the Radeon HD 4870 X2 delivers good performance and outpaces the GeForce GTX 280 in this test. The gap is especially large at 2560x1600 where the Radeon HD 4870 X2 enjoys a 45% lead in terms of average speed. ATI’s solution also features superb stability which is not observed with the classic CrossFire tandem.

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.

The Radeon HD 4870 X2 is roughly equal to the Radeon HD 4870 CrossFire configuration at ordinary display resolutions but goes ahead at 2560x1600, leaving all its opponents far behind. The reason is obvious: the game features MegaTexture technology that operates with 32768x32768 textures (they are as heavy as 3 gigabytes in uncompressed form), so 1 gigabyte of local graphics memory comes in handy here.

Half-Life 2: Episode Two

Joining two RV770 chips on a single PCB by means of a PCI Express switch is unrewarding in Episode Two. It is only at a resolution of 2560x1600 that the single-PCB implementation of CrossFire technology has a 5% lead over the two-PCB implementation. The Radeon HD 4870 X2 maintains its winning reputation because the GeForce GTX 280 has a considerably lower average frame rate at the highest resolution. The tradeoff of the highest performance is power consumption. As you remember, the new card consumes over 200W under 3D load.

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.

The Radeon HD 4870 X2 doesn’t show anything exceptional in S.T.A.L.K.E.R. because this game doesn’t make use of 1 gigabyte of memory whereas the other parameters of the new card are the same as those of the Radeon HD 4870 CrossFire configuration. Anyway, it takes the top position, delivering comfortable average and bottom speeds at 2560x1600.

Performance in Third-Person 3D Shooters

Lost Planet: Extreme Condition

The Radeon HD 4870 X2 doesn’t differ much from the two Radeon HD 4870 cards working in CrossFire mode except at 2560x1600 where the former card is 21-22% faster. This victory has little practical value because an average speed of 7fps cannot be called comfortable. The result doesn’t differ from the result of the single Radeon HD 4870, so either CrossFire technology is not supported well for this game, notwithstanding the lower resolutions, or it cannot work normally due to some specifics of the game engine.

Tomb Raider: Legend

Nvidia’s superiority in this test has been questioned by the Radeon HD 4870 X2. The new card outperforms the GeForce GTX 280 at 1600x1200 and 2560x1600 but loses at 1280x1024 and 1920x1200. The new card has no problems with multi-GPU technology although we could not achieve any performance growth with the traditional Radeon HD 4870 CrossFire tandem.

Performance in RPG

Hellgate: London

The game needs a lot of graphics memory as is indicated by the results of the GeForce GTX 280 but the Radeon HD 4870 X2 has the same amount of memory and wins at 2560x1600. Nvidia’s card is superior at resolutions below 1920x1200, though. That’s not a problem since the new card’s frame rate is always playable. The Radeon HD 4870 X2 seems to be worth its price here.

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.

The Radeon HD 4870 X2 doesn’t show anything revolutionary in this game, but no revolution is called for, actually. The game is not a heavy application for today’s graphics cards. The bottom speed of the ATI solution is somewhat below the required minimum in open scenes at 2560x1600 whereas the GeForce GTX 280 always delivers a comfortable frame rate. Perhaps the Sideport interface, when enabled, will solve even this small problem.

Performance in Strategies

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 quality of the visuals.

This is another win for ATI. Its product sets a new record at 2560x1600 in terms of both average and bottom speed. Although the bottom speed doesn’t reach 25fps, the Radeon HD 4870 X2 is the best card for playing this game. The additional data-transfer channel between the RV770, if enabled, may increase its performance even further.

Command & Conquer 3: Kane’s Wrath

The add-on to C&C 3: Tiberium Wars brought no changes into the technical aspect of the game. The game still having a frame rate limiter, you should consider the minimum speed of the cards in the first place.

Command & Conquer 3 doesn’t make a good benchmarking tool for today’s top-performance solutions because they all have the same results in it. We are going to replace this test with something heavier soon.

World in Conflict

Like in CoH: Opposing Fronts, the Radeon HD 4870 X2 doesn’t show any breakthroughs, but offers the highest speed at 2560x1600, being the only solution to ensure maximum comfort with 4x MSAA. None of Nvidia’s single graphics cards is anywhere near the results of the Radeon HD 4870 X2.

Performance in Synthetic Benchmarks

Futuremark 3DMark06

The Radeon HD 4870 X2 didn’t set any new records in 3DMark06 but this version of the benchmark is not really difficult for modern graphics hardware. The card of such tremendous potential as ATI’s new solution just cannot show its full strength here. So, it is always slightly worse than the Radeon HD 4870 CrossFire tandem in every overall score, but those scores are obtained at 1280x1024 without FSAA.

The individual SM2.0 tests agree with the overall scores: the Radeon HD 4870 X2 is somewhat slower than the Radeon HD 4870 CrossFire, but the difference is very small.

The same is true in the second SM3.0/HDR test while in the first test the two solutions from ATI equal each other with a difference of only 0.3fps.

Futuremark 3DMark Vantage

We minimize the CPU’s influence by using the Extreme profile (1920x1200, 4x FSAA and anisotropic filtering).

Unlike 3DMark06, 3DMark Vantage uses all the resources a modern graphics card can offer including memory. The Radeon HD 4870 X2 has twice as much memory as the Radeon HD 4870 CrossFire and the resulting gap between them amounts to almost 900 points. The GeForce GTX 280 is far behind the leader, indicating the main flaw in the design of Nvidia’s new GPU which has high texture-mapping performance but very modest computing capabilities.

Notwithstanding the disabled Sideport, the Radeon HD 4870 X2 is 20% more efficient than the ordinary CrossFire configuration built out of two Radeon HD 4870 cards. It must be because of the larger amount of graphics memory because the Extreme profile uses 1920x1200 resolution with 4x MSAA. The advantage is smaller in the second test, only 12%, yet it is still a triumph for ATI.

Conclusion

It is time to summarize our experience with the Radeon HD 4870 X2 now. The new card’s results in out tests are highly optimistic in general, with very few exceptions. As usual, we will show you a few summary diagrams for every display resolution.

The Radeon HD 4870 X2 starts out briskly, winning eight out of the 16 tests. It enjoys an 80% lead over the GeForce GTX 280 in Call of Juarez and a 15% lead in two more games. The new card is slower than its opponent in seven tests but the gap is large in only three tests, including World in Conflict. Still, the Radeon HD 4870 X2 easily provided a comfortable frame rate in both CoH: Opposing Fronts and Hellgate: London. Moreover, such an expensive and advanced graphics card as the Radeon HD 4870 X2 is not really meant for playing at 1280x1024, so these results have little practical value.

At a display resolution of 1600x1200, the Radeon HD 4870 X2 is inferior to the GeForce GTX 280 in only three tests. And its frame rate is quite playable in every of these three. In the other tests, save for Command & Conquer, ATI’s flagship outperforms the ex-leader of the 3D world by 1.7% in one test to as much as nearly 100% in another!

We see a similar picture at a resolution of 1920x1200 but the Radeon HD 4870 X2 has a greater advantage over the GeForce GTX 280 now. It is 10-15% in more tests and over 100% in Call of Juarez. The new card’s victory in 3DMark Vantage should also be counted in because the Extreme profile uses 1920x1200 resolution.

The resolution of 2560x1600 was the triumph for the Radeon HD 4870 X2. The new card was developed for that and it fulfilled its purpose. The double amount of graphics memory helped it win in almost every test, except for Call of Duty 4 where the gap from the GeForce GTX 280 is a mere 6% anyway. Moreover, the Radeon HD 4870 X2 provides a comfortable or near-comfortable speed in every game save for Crysis, Lost Planet and World in Conflict. So, it is the first graphics card that makes the resolution of 2560x1600 truly available for practical gaming!

We should confess the new card is not absolutely free from drawbacks. First of all, it consumes too much power. It is the first time in our tests that we have a graphics card that consumes far more than 200 watts. This also means the card generates a lot of heat. To dissipate this heat, the cooler’s fan has to operate at a high speed, producing a lot of noise. So, in order to achieve such a high level of performance, you have to use a really high-wattage power supply and you have to put up with the hotness and noisiness of your Radeon HD 4870 X2.

The classic drawback of homogeneous multi-GPU solutions – the lack of performance growth when not supported on the software level – persists too, even though it is not as serious as before. Judging by our tests, ATI has nearly got rid of it, but there are far more games available on the market, and we cannot be sure this problem won’t show up in some of them. Hopefully, ATI will be collaborating with game developers to solve such problems as quickly as possible.

All in all, ATI has confirmed its claim for leadership in building consumer 3D graphics hardware. The Radeon HD 4870 X2 is indeed the highest-performance card for today. However, it is not a direct opponent to the GeForce GTX 280 because it costs somewhat more money.

Talking about the particular version of the card, the PowerColor HD 4870 X2 2GB GDDR5 is a typical reference card without special accessories. If you buy it, you’ll get only what you pay for, i.e. the fastest graphics card available today.

PowerColor HD 4870X2 2GB GDDR5 Summary

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