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:
| |
ATI Radeon™ HD4870 |
ATI Radeon™ HD4850 |
ATI Radeon™ HD3870 |
| Q-ty of transistors, mln |
965 |
965 |
666 |
| Process technology, nm |
55 |
55 |
55 |
| Streaming processors |
800 |
800 |
320 |
| Texture units |
40 |
40 |
16 |
| Rastering units |
16 |
16 |
16 |
| GPU clock speed, MHz |
750 |
625 |
775 |
| Type and effective frequency of the video memory |
GDDR5, 3600 MHz |
GDDR3, 2000 MHz |
GDDR4, 2250 MHz |
| Computational power of the GPU, TFlops |
1,2 |
1,0 |
0,497 |
| Bus type |
PCI Express 2.0, x16 |
PCI Express 2.0, x16 |
PCI Express 2.0, x16 |
| Support for DirectX |
10.1 |
10.1 |
10.1 |
| Tessellation unit |
yes |
yes |
yes |
| Integrated video decoder |
ver. 2.0 |
ver. 2.0 |
ver. 1.0 |
| Support for ATI PowerPlayTM |
yes |
yes |
yes |
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:
| Test configuration |
| CPU |
Intel Core 2 Quad X6850 3.0 GHz |
| Motherboard |
ASUS P5E3 (Intel X38) |
| RAM |
Corsair Dominator DDR3 2 x 2 GB 1333 MHz 6-6-6-18 1T |
| Operating system |
Windows XP+SP2+DirectX 9.0c / Windows Vista for DX10 tests |
| Power supply unit |
Thermaltake Toughpower 750 W |
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.
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