Radeon HD4870 - a new king in the top-middle class

A bit of theory

To understand the quality differences of the new graphic chip RV770 from the models of the two previous generations, it suffices to take a look at its schematic diagram.

The differences are evident if we compare the diagram against the one used in R600/RV670. The texture units in the new chips are linked to the streaming processors, and AMD has seriously reworked the circuitry of L1 and L2 cache integrated into the GPU, the ROP units have been improved, with the number of streaming processors increased to 800.

The antialiasing engine has undergone serious changes, which resulted in a substantial increase in speed, and the 2x/4x MSAA has now turned almost free! In the our forthcoming reviews, we'll dwell on that in more detail, as well as compare the quality of antialiasing for AMD and NVIDIA video cards. For reference, we bring in a table of specifications for the new video cards and compare them against the previous generation:

We'll be examining Radeon HD4870 on the example of a video card provided by HIS for running the tests.

HIS Radeon HD4870

The package for HIS Radeon HD4870 is small in size and is made in blue tints. Both sides of the box display the key info on the video card.

The package bundle includes the following items:

• DVI -> D-Sub adapter;
• DVI -> HDMI adapter;
• S-Video > RCA adapter;
• S-Video/Component out adapter;
• CrossFire bridge;
• drivers CD;
• user's manual, an info sheet on available Steam games;
• a sticker for the housing;
• proprietary "screwdriver-lamp-level gauge";

The package bundle of the video card lacks power adapters, but there is a proprietary screwdriver with a lamp and a level gauge. Let's see:

The bundled screwdriver is shipped with two nozzles, each equipped with two heads. The first nozzle is meant for handling flat caps, the second one - for cross-shaped. A level gauge is mounted into the housing of the screwdriver.

Near the jack for fitting the nozzles, there is a lamp based on a super-bright LED. The switch is positioned near the level-gauge, and there is no need to hold it with fingers because that is just a switch and not a button.

The video card inside the box makes almost no difference from that demonstrated to the whole world by AMD, with the exception that the sticker on the fan is proprietary, made by HIS. To apply power to Radeon HD4870, there are two 6-pin connectors in the tail part of the video card, versus merely one connector in the lower-end Radeon HD4850. An advanced power supply system was required for a stable operation of the video card at increased frequencies. As compared to Radeon HD4850, the GPU frequency of Radeon HD4870 is 125 MHz higher and equals 750 MHz, with the effective frequency of GDDR5 video memory being 3600 MHz, which is much higher than the 1986 MHz at which the video memory in Radeon HD4850 runs. But we should make a reservation here that the real frequency of the new GDDR5 memory equals 900 MHz, simply because it transmits four, not two, times as much of data as compared to the "regular" non-DDR memory.

The cooling system of the video card very much resembles that used on Radeon HD2900XT video cards. The copper insert with two heat pipes and aluminum sheets serves to cool the GPU; the housing made of an aluminum alloy cools the memory chips and the chips of the power supply subsystem, as well as adds to the rigidity of the whole structure. To prevent warping of the copper insert and therefore damage to the graphic chip, it is made independent of the metal framework.

Among the external differences, as compared to Radeon HD4850, in Radeon HD4870 the power supply subsystem has been changed, with an AMD logo appeared above the PCI-express x16 slot. Although the new video card is equipped with the latest GDDR5 video memory, its positioning on the PCB makes no difference from that for GDDR3 memory on Radeon HD4850.

Radeon HD4870 uses the same RV770 graphic chips as on Radeon HD4850.

The GDDR5 video memory chips are made by Qimonda. The nominal effective clock speed for this memory is 4.0 GHz, while rated frequency at which the memory runs on Radeon HD4870, as we already stated, equals 3.6 GHz.

Under load in the 3D mode, the graphic chip of Radeon HD4870 runs at 750 MHz, while in the idle time its frequency drops to 500 MHz.

Efficiency of the cooling system and overclocking

Since neither Riva Tuner nor any other program that does overclocking of ATI/AMD video cards has not so far supported the new family Radeon HD4000, we'll briefly tell of the temperature measurements and other indicators. During the idle time, the temperature of the GPU fluctuates at about 78 C, with the fan rotating at 1075 RPM, which makes 22% of its maximum possible speed. Under load, that is, while running nine Firefly Forest tests of the 3DMark’06 suite at 1600?1200 with 4x FSAA and 16x AF, the graphic chip heated up to 84 C. In so doing, the fan's rotational speed went up to 1886 RPM, which makes 30% of the maximum possible speed. Note that at this speed the noise from the cooling system became more audible.

As regards the overclocking, the only available method for effecting that is currently the ATI Overdrive utility integrated into the control panel of the video card. Alas, the utility does not provide any freedom of action in raising the frequency of the graphic chip by merely 40 MHz, and 200 'true' MHz for the memory. In the end, we were lucky to overclock Radeon HD4870 to 790/4400 MHz, which is no fun. However, we did manage to test the overclocked Radeon HD4870 in Crysis, and at the end of this review you will take a look at the results of this small experiment.

The Tests

We'll be running the tests with the following configuration:

We used the following video cards and drivers as contenders for Radeon HD4870 by HIS:

• GeForce GTX280, ForceWare 177.34;
• GeForce GTX260, ForceWare 177.39;
• Radeon HD4850, Catalyst 8.6;

For the new video card, like for Radeon HD4850, we used Catalyst 8.6 drivers. We'll be running our tests in both the "regular" and increased resolutions. We start with 3DMark tests and "standard" screen resolutions.

Tests in standard resolutions

At 3DMark tests, the new product by HIS scored much more points than its lower-end value "sister" Radeon HD4850, which allowed it to perform on par with competitors by NVIDIA. But, as we already stated in our previous articles, 3DMark tests do not reveal the whole picture. Gaming tests is quite a different thing, so we'd better get round to them. As usual, we ran the tests with 4X FSAA and 16X AF enabled.

In the very first test, Radeon HD4870 was flexing its "muscles". At Call of Duty 4, the new product was able leaving GeForce GTX260 behind. As we will see further, that will not be always like that.

Here you are. Crysis powered by Windows XP. The results for Radeon HD4870 are close, but anyway a bit lower than the results for GeForce GTX 260.

The situation almost has not changed under Windows Vista - Radeon HD4870 is slower at that as well than GeForce GTX 260.

At Need for Speed Pro Street Racing, the situation proved a bit different - in two resolutions of three, the new product proved to be faster than GeForce GTX 260. The loss at 1600x1200 can be attributed to the smaller capacity of video memory in Radeon HD4870.

At Call of Juarez, the results for Radeon HD4870 ranked between the results for GeForce GTX 260 and GeForce GTX 280. This game has always been demanding to the performance of the shader unit and "favorable" to video adapters by AMD.

On switching to Windows Vista, the situation changes in favor of GeForce GTX 260, although at 1600x1200 the Radeon HD4870 anyway proves to be faster. Since in Call of Juarez powered by Windows Vista the load upon the video memory increases, it is logical to assume that GeForce GTX 260 owes for its victory at low resolutions to its wide memory bus width 448 bit, but with the rise of resolution it lacks the capacity of the shader unit, so Radeon HD4870 proves to be faster.

We see a similar picture at Need for Speed Carbon where with the rise of resolution the Radeon HD4870 turns out to be even faster than GeForce GTX 280!

At "Prey", we see the same pattern: the resolution is rising, whereas the loss of Radeon HD4870 to the rivals by NVIDIA is shrinking. However, in the previous reviews we pointed to the fact that new video cards by AMD feel very comfortable at high resolutions. On the other hand, the small capacity of video memory in AMD video cards may play a bad trick to it, of which we'll report a bit later.

Tests in high resolutions

At Crysis with high quality settings, Radeon HD4870 is increasingly lagging behind GeForce GTX 260 as resolutions go up, which is caused by its small video memory capacity according to modern standards.

On switching to the maximum possible quality settings, at the first two resolutions Radeon HD4870 turns out to be at least on par as compared to GeForce GTX 260. However, at the maximum resolution 2048x1536 the results drop substantially. And again, the insufficient video memory capacity is to blame for. Perhaps, the versions of Radeon HD4870 with 1 GB video memory capacity (if such ever appear) will demonstrate much better results. The lag of Radeon HD4870 behind its "lower-end" sister Radeon HD4850 is perhaps attributed to the specifics of GDDR5, but we'll go into that in our forthcoming materials.

Amusingly, but just in Windows Vista which is more demanding for the video memory capacity than Windows XP Radeon HD4870 feels more comfortable and does not demonstrate a speed drop at 2048x1536. On the other hand, in Radeon HD4870 and Radeon HD4850 there is an issue with the resolution 1920x1200 at which the game runs but no image is displayed. To all appearances, that is caused by a flaw in the drivers.

On switching to the maximum possible settings, the speed goes down but the overall alignment of forces does not change.

At Call of Juarez under Windows XP, even after switching to high resolutions Radeon HD4870 proves to be faster than GeForce GTX 260.

On switching to Windows Vista, GeForce GTX 260 appears to be faster in only the lowest resolutions, and in the higher resolutions the Radeon HD4870 takes a lead. This once again points to a more powerful shader unit in the video card by AMD.

At Call of Duty 4 in high resolutions, Radeon HD4870 performs on par with GeForce GTX 260. Almost the same situation was observed in the lower resolutions.

At Race Driver: GRID, Radeon HD4870 yields to GeForce GTX 260 at only the highest resolution. Most likely, the relatively small video memory capacity was to blame for that.

Tests of overclocked Radeon HD4870 in Crysis

Lastly, as we promised, here are the results for Radeon HD4870 overclocked to 790/4400 MHz tested in Crysis:

The speed gain is evident. As you can see, further increase in the clock speed could have made the new product much faster. But for now, there are no utilities able doing that so far.

Final Words

Radeon HD4870 has proved to be a real competitor to GeForce GTX 260. We have not seen things like these so far - top-end representatives of the previous two families of video cards by AMD were able competing against the produce of NVIDIA only on words, but in fact they used to be too slow. Evidently, the new shader unit with the increased number of streaming processors and the modified architecture proved to be more powerful than the shader unit in GeForce GTX 260. But the new product is not up to the mark versus GeForce GTX 280, at the same time it provides a comfortable gameplay in almost all modern games.

With the recommended price 299$, Radeon HD4870 can already be made available at 460$. At the same time, GeForce GTX 260 costs about $100 as much. With this amount you can buy a couple of Radeon HD4850 which can be merged into CrossFire combination, which should be faster in terms of performance than GeForce GTX 260. And a CrossFire combination of two Radeon HD4870 is quite easy to oppose against GeForce GTX 280. By the way, AMD has promised substantial improvements in the operation of its multi-chip configurations, but that is a topic for our forthcoming review.