The Best May Be Even Better: ATI Radeon HD 4870 X2 Overclocked

New dual-chip ATI Radeon HD X2 graphics card family proved that AMD graphics division deserves to be a technology leader. Today we are going to talk about HIS HD 4870 X2 HDMI 2GB GDDR5 graphics card and will find out if overclocking helps this flagship solution to increase its performance even more.

by Alexey Stepin , Yaroslav Lyssenko
10/17/2008 | 03:05 PM

The ATI Radeon HD 4870 X2 model is deservedly considered the fastest graphics card in the consumer class. Being the most striking illustration of ATI’s new development strategy, this dual-headed monster easily ensures comfortable playing conditions in most of today’s games even at a resolution of 2560x1600 but demands 260 watts of power and produces quite a lot of noise.


The GPU developers seem to have reached the limit beyond which it is impossible to increase performance any further due to the constraints imposed by the capabilities and dimensions of cooling systems. The dual-slot form-factor of the cooler has long become standard in modern gaming PCs, but even such coolers can barely cope with the heat generated by the two RV770 cores of the Radeon HD 4870 X2.

We will hardly see unique versions of this graphics card. The dual-processor design leads to most sophisticated PCB wiring and also makes it unprofitable for third-party developers to devise more effective coolers than the reference one. Such coolers are meant to be universal, but a cooler developed for the Radeon HD 4870 X2 wouldn’t fit any other card. And $500 cards account for but a negligible share of the total sales of desktop discrete graphics solutions. Of course, some makers such as ASUS and CoolIT have announced exclusive coolers for ATI’s dual-headed monster, but they are talking about liquid cooling systems which are very specific solutions themselves.

Factory overclocking of a Radeon HD 4870 X2 is a rather fruitless effort and even a dangerous one with the reference cooler that already works at its limit, so ATI’s partners have to appeal to the potential buyer with such time-tested means as pretty-looking packaging and rich accessories with something special.

One such card is going to be reviewed today. It is the HD 4870 X2 HDMI 2GB GDDR5 model from HIS. Besides checking it out for anything unusual, we will try to estimate the overclocking potential of an ordinary off-the-shelf Radeon HD 4870 X2 and see if such overclocking can be rewarding.

Package and Accessories

Although the HIS HD 4870 X2 belongs to the top product category, its box isn’t huge or special in any way. The design is nice, though. The abstract drawing resembling a stylized fan and airflow looks better to us than hackneyed monsters, robots or busty girls in armor.

This box can’t match the restrained design of products of Club3D or Sapphire Toxic cards, yet it’s good anyway. You can find some typical technical info on the box. Its protective properties are perfectly standard, too. Included with the PSU are the following accessories:

The accessories are not scanty and seem to match the product’s status but we’ve got a couple of gripes about them. Our main gripe is about the lack of a full-featured player of HD video. The trial version of CyberLink PowerDVD included into the Platinum Pack can only be used for a limited time. This kind of economy doesn’t look right to us considering the price category the Radeon HD 4870 X2 belongs to.

The screwdriver is a nice accessory but is it really so useful? We guess every PC enthusiast who upgrades his computer with his own hands has even handier and better tools. The screwdriver from HIS isn’t very practical inside a cramped PC case due to the thick handle and short interchangeable nozzles but the integrated flashlight may come in handy. We wonder what use the bubble level integrated into the screwdriver can be for a devoted gamer, though. So, this screwdriver is a cute toy that you may want to use if there is no serious tool at hand. And you can take it with you on your LAN parties as it will fit into your pocket easily.

Otherwise, the accessories of the HIS HD 4870 X2 are standard, including all the cables and adapters you may want today. Perhaps they are not as gorgeous as the accessories included with Sapphire’s products, but anyway. We don’t have much to say about the packaging, either. It is not particularly eye-catching, but looks neat in comparison with the numerous monsters and cyborgs you can see on other boxes.

PCB Design and Cooling System

All Radeon HD 4870 X2 cards are copies of the reference samples because they are all made under control and according to the specifications of ATI. The HIS HD 4870 X2 makes no exception as its only distinguishing trait is the sticker on the cooler’s fan.

The PCB is 27 centimeters long just as you could expect from a graphics card that has two graphics cores, two sets of memory chips, a PCI Express switch, and an advanced power circuit. Developing a similar product, Nvidia even used a dual-PCB design whereas ATI’s engineers limited themselves to a single PCB. The HIS HD 4870 X2 is meant for top-end gaming systems that cannot be compact, so there shouldn’t be any installation-related problems. Each GPU is powered by a dedicated three-phase voltage regulator based on a Volterra VT1165MF controller. The card has two power connectors, a 6-pin and an 8-pin one. An appropriate cable must be attached to the latter because its load is almost two times as high as the maximum load of the 6-pin connector (75W). Therefore any experiments with “cheating” the power circuit are not recommended.

A PLX Technology PEX8647 chip serves as a PCI Express switch here. It offers full support for PCI Express 2.0 and can establish direct communication between the GPUs in peer-to-peer mode. Two RV770 chips are installed on both sides of it. Each GPU is clocked at 750MHz and incorporates 800 ALUs, 40 texture processors and 16 raster back-ends. There is not much elbowroom for overclocking because the Radeon HD 4870 X2 generates as much as 260W of heat even at its default frequencies, its cooler barely coping with that.

Each graphics core has a dedicated 1GB bank of local graphics memory consisting of eight GDDR5 chips from Hynix (H5GQ1H24MJR-T0C, 1Gb capacity, 32Mb x 32). The chips have a rated frequency of 900 (3600) MHz and are indeed clocked at it on this card. The total amount of graphics memory that applications can access is not 2GB but only 1GB due to the specifics of the card’s architecture. 1 gigabyte is quite enough even for the most demanding of today’s games, though. But since the contents of each memory bank are duplicated, the total bandwidth of the memory subsystem is two times as high as that of the Radeon HD 4870, namely 230.4GBps against 115.2GBps. This is far higher than the memory bandwidth of any solution from Nvidia, including the GeForce GTX 280 with its 512-bit memory bus.

The card is equipped with a standard set of interfaces including two dual-link DVI-I ports, a universal 7-pin port for analog video output, and a CrossFire connector. The latter allows combining two Radeon HD 4870 X2 cards into a single graphics subsystem with a total of four GPUs. Such a subsystem should deliver unprecedented performance and we will check this out when we transition to 64-bit Windows Vista that removes all memory-related limitations. The RV770 incorporates an audio core, so you don’t have to connect to your sound card via S/PDIF. A DVI-I → HDMI adapter is enough.

The cooling system of the Radeon HD 4870 X2 is surprisingly simple for a card with a heat dissipation of 260 watts. It consists of two separate copper heatsinks, one of which has an evaporating chamber. These heatsinks cool the graphics cores whereas the other components such as the PCI Express switch, memory chips and load-bearing components of the power circuit are cooled with the aluminum frame of the cooler that has juts and elastic thermal pads at the appropriate places. A separate metallic plate cools the memory chips located on the reverse side of the PCB.

The heatsinks are cooled by a 12W fan from NTK Technologies (CF1275-B30H-C004). It doesn’t work at its full speed as the noise would be just unbearable then. The hot air is exhausted through the slits in the card’s mounting bracket. The plastic casing of the cooler has a sticker warning you about the high temperature of the metallic parts. Indeed, this precaution is necessary as those parts become scorching hot at work.

Generally speaking, the cooler of the HIS HD 4870 X2 (and of any other Radeon HD 4870 X2) illustrates the dead end the graphics card makers have found themselves in when they need to dissipate over 200 watts of heat while staying within the constraints of the dual-slot form-factor. We guess a single copper heatsink reinforced with heat pipes would be more efficient, but its weight would be too high. Alternative coolers are unlikely to appear in mass quantities due to the dual-chip design of the card although some makers, such as ASUS and CoolIT, have already announced liquid cooling systems for Radeon HD 4870 X2.

Power Consumption, Overclocking, Temperature

We had already published the results of our measurements of the power draw of the Radeon HD 4870 X2, but this time we tried to overclock the HIS card and measured its power draw at the overclocked frequencies on the following testbed:

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. 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.

Unfortunately, the overclocking attempt was not much of a success. We could only increase the GPU frequency from the default 750MHz to 800MHz. The memory chips refused to overclock at all: the system would hang up or show visual artifacts when we tried to increase the card’s memory frequency. So, the power consumption tests yielded the following results for the GPU frequency of 800MHz:

Click to enlarge

The HIS HD 4870 X2 consumes over 270 watts of power, which is a new record. As expected, the load grew up the most on the 8-pin power connector. The HIS card consumes 10.8 watts more than the reference sample, and it is clear now why overclocking a Radeon HD 4870 X2 is a daunting task. According to the Catalyst Control Center, the GPUs were as hot as 92-95°C under load. You must take care about proper ventilation of your system case if you want to install a Radeon HD 4870 X2, let alone overclock it. 

The level of noise is the same as that of the reference card (for deatils see our article called ATI Radeon HD 4870 X2 Graphics Accelerator: New Champion ). The card is noisy in 3D mode and the periodic changes of its noise level are rather irritating. That’s the price you have to pay for the tremendous performance of the Radeon HD 4870 X2. You have to put up with that or think about installing a liquid cooling system. And it must be an advanced system capable of dissipating over 250 watts of heat. Inexpensive models widely available on the market just won’t cope with this card.

Testbed and Methods

For our performance tests of HIS HD 4870 X2 HDMI 2GB GDDR5 in contemporary games 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



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 HIS HD 4870 X2 HDMI 2GB GDDR5, we 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 HIS solution belongs to the top price range, we expanded the standard set of resolutions with 2560x1600  available to 30-inch display owners. 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. In this case we ran tests several times and took the average result for the diagrams. 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 1920x1440 and 2048x1536 pixels (4:3 format) instead of 1920x1200 and 2560x1600 here.

It is clear that the frame rate is not limited by the HIS HD 4870 X2 in this game notwithstanding 4x FSAA. The average and bottom speed are almost the same at every resolution, and there is no benefit from overclocking. The Radeon HD 4850 CrossFire subsystem and Nvidia’s GeForce GTX 280 behave in a similar way, the latter being even preferable in terms of power consumption and heat dissipation.


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

CrossFire related problems have been corrected in the new version of ATI’s Catalyst. CrossFire tandems consisting of two standalone Radeon HD cards now deliver good performance in this game. Particularly, the Radeon HD 4850 CrossFire subsystem is no worse than the Radeon HD 4870 X2 at resolutions up to 1600x1200/1680x1050 inclusive. The flagship of the Radeon series goes ahead at the higher resolutions, but the gap isn’t large. It amounts to 25% at 2560x1600 and the Radeon HD 4850 CrossFire provides a comfortable frame rate at that resolution, too. We guess the gap from a Radeon HD 4850 X2 would be even smaller.

The overclocking of the HIS card leads to a 5% increase in performance at the highest resolution. You just can’t expect anything more from a 50MHz increase in GPU frequency.

Call of Juarez

The game doesn’t support resolutions above 1920x1200, so there are no results for 2560x1600.

The overclocking is more rewarding in this game, resulting in a 10% increase in average speed at a resolution of 2560x1600. The bottom speed grew by only 1fps, though. Anyway, the Radeon HD 4870 X2 is still the only graphics card that can provide a playable frame rate in Call of Juarez at the highest graphics quality settings.

Call of Duty 4: Modern Warfare

There is a 5% performance gain due to overclocking at 2560x1600. This has no effect on the gamer’s experience, yet we can see that the overclocked Radeon equals the GeForce GTX 280. Nvidia’s solution is preferable in terms of power consumption even though it is inferior to the two RV770 cores equipped with GDDR5 memory at the lower resolutions.


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.

The overclocked Radeon HD 4870 X2 acquires a 5% performance bonus in this game. That’s not much of an advantage, of course. Nvidia’s G200-based solutions still ensure smaller fluctuations of speed and, accordingly, more comfort in this game, but even they cannot maintain a frame rate of 25fps or higher.

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 GeForce GTX 280 is in the lead until the resolution of 2560x1600 where the Radeon HD 4870 X2 goes ahead thanks to its higher memory bandwidth and efficient memory management. This has no practical value due to the frame rate limiter: the GeForce GTX 280 is twice as fast as necessary, for example. Like in the previous tests, the overclocking increases the average performance of the HIS card by a mere 5%.

Half-Life 2: Episode Two

The Radeon HD 4870 X2 wins this test. Although its lead over the GeForce GTX 280 is rather small at low resolutions, the gap grows to 8% and 30% at the more important resolutions of 1920x1200 and 2560x1600 pixels, respectively. The overclocking leads to a 4% increase in speed, which has no practical value. So, you may only want to overclock your HIS HD 4870 X2 just as a hobby unless you use some extreme overclocking methods. But if you overclock the card in an extreme way, it will hardly work for long in such a mode.

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.

There is an effect from overclocking at every resolution. For example, there is a 9-10% increase in the card’s bottom speed at a resolution of 1280x1024. The 50MHz growth of the GPU frequencies leads to a 6% growth of the average speed at 2560x1600. Like in the previous tests, this has no effect on your playing comfort.

Performance in Third-Person 3D Shooters

Lost Planet: Extreme Condition

The HIS HD 4870 X2 speeds up at every resolution when overclocked, but its bottom speed doesn’t change, which means that the card is still limited to 1920x1200 in this game. Well, we didn’t actually hope that there would be a performance breakthrough at 2560x1600 just because we had increased the GPU frequencies by 50MHz.

Tomb Raider: Legend

CrossFireX subsystems work normally in this game after the release of ATI Catalyst 8.8, yet the Radeon HD 4850 CrossFire still cannot deliver a comfortable frame rate at 2560x1600. The HIS HD 4870 X2 feels all right at that resolution. Overclocking just adds it a little more speed. The only exception is the resolution of 1600x1200 where the GeForce GTX 280 is superior for some reason.

Performance in RPG

Hellgate: London

ATI’s flagship is considerably slower than the cheaper and more economical GeForce GTX 280 at resolutions below 1920x1200 and has a far lower bottom speed at 1920x1200. But it provides a higher average frame rate at 2560x1600 although Nvidia’s card maintains a playable speed, too. Overclocking doesn’t change anything in the overall picture, adding just a few percent to the already high speed of the HIS HD 4870 X2.

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 performance of the HIS HD 4870 X2 improves by 10% at 2560x1600 in the closed environments. At the other resolutions the performance grows by 4-5% only, which is quite a normal consequence of a 50MHz increase in GPU frequencies and no improvement in memory frequency.

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.

When overclocked, the HIS card becomes 7% faster at 2560x1600 as opposed to 4-5% in most of other tests. This won’t affect the gamer’s experience, however. The smoothness of gameplay and the accuracy of control will remain at the same level, somewhat below comfortable, because the bottom speed is below 20fps in both cases.

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.

This game is no good for benchmarking top-performance graphics cards anymore as all of them deliver the same results. We are going to replace this test with something newer soon.

World in Conflict

The overclocked HIS HD 4870 X2 has a somewhat higher bottom speed at some resolutions, but it is not enough to make the gameplay really smooth. The bottom speed of the overclocked card even dropped at 1280x1024. Anyway, the Radeon HD 4870 X2 is one of the best solutions for playing this game.

Performance in Synthetic Benchmarks

Futuremark 3DMark06

We did not set any records by overclocking the card from HIS. It didn’t reach an overall score of 14,000 points even. There is nothing particularly interesting in the groups of tests, either. Let’s see how the increased GPU frequencies of the Radeon HD 4870 X2 affect the results of the individual 3DMark06 tests.

The HIS card wins both tests. Compare the results of the Radeon HD 4870 X2 and Radeon HD 4850 CrossFire: they are identical notwithstanding the difference in frequencies and memory type.

There is a bigger effect from overclocking in the two SM3.0 tests: 15% and 10%, respectively. Like in the SM2.0 tests, the HIS HD 4870 X2 at the default frequencies is inferior to the Radeon HD 4850 CrossFire configuration. We can’t explain this behavior, especially as it doesn’t agree with the results of our gaming tests.

Futuremark 3DMark Vantage

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

The Radeon HD 4870 X2 does not get any faster in 3DMark Vantage when its GPUs are overclocked by 50MHz. This must be due to the lack of memory frequency growth despite the tremendous combined bandwidth of the two GDDR5 memory banks.

It is only in the second that we can find a 2-3% growth of speed whereas the first test doesn’t show any difference. The individual tests agree with the overall scores.


It’s time to sum up our experience with the HIS HD 4870 X2 HDMI 2GB GDDR5 graphics card. It is hard to say something new about its performance because this card is a precise copy of the reference Radeon HD 4870 X2 in everything including specifications and has all of the latter’s highs and lows. Yes, this card delivers unprecedented performance in games, especially at resolutions above 1600x1200/1680x1050 pixels. And it just has no rival at 2560x1600.

Confirming ATI’s technological superiority, this card is not free from drawbacks, however. First of all, it has a terrific level of power consumption and heat dissipation. And second, its performance, like that of any multi-GPU solution, depends on driver optimizations. The high level of high dissipation leads to a high level of noise. The cooler with a rather modest heatsink works at its limit to dissipate 260 watts of heat. The GeForce GTX 280 has somewhat worse performance at resolutions up to 1920x1200 but looks very economical in comparison. Thus, the HIS HD 4870 X2 targets those users who need the highest performance whatever the price, power consumption or noise may accompany it. From this point of view, the card is superb, especially as the second problem of multi-GPU solutions – the dependence on software optimizations – does not show up often with the new generation of ATI’s dual-chip solutions.

Just as we had expected before this test session, the Radeon HD 4870 X2 is no good for overclocking. ATI’s engineers have already squeezed everything out of it. This can be illustrated with the summary diagrams:

The increase of the GPU frequencies by 50MHz provided a certain effect which amounted to a 10% increase in performance in some tests. However, in most tests there was a performance growth of only 4-5%. We don’t think this result is worth the trouble of overclocking. Moreover, the biggest effect is observed at a resolution of 2560x1600, which is used by few gamers. At the lower resolutions there is a small or zero increase in performance.

The packaging and accessories of the HIS card are good, but the accessories might reflect the product’s elite status more. Particularly, the box does not contain a power adapter for an 8-pin PCI Express 2.0 connector and software for playing HD video. The former accessory is important because the power consumption on this channel is almost two times as high as the load capacity of the 6-pin power connector (75W). The lack of a HD video player is odd considering the pricing of the product.

So, the HIS HD 4870 X2 HDMI 2GB GDDR5 is going to suit gamers who want the highest speed possible and have a 24-inch or larger monitor. For other people this performance may prove to be redundant, especially as this device is highly uneconomical, because the card’s resources are often not utilized fully at resolutions below 1920x1200 pixels.