ATI’s Radeon HD 4000 series are supposed to mark the return of this brand in the performance race.  And indeed since the release of Nvidia’s GeForce 8s, the manufacturer with the red logo has had problems offering chips with high performances in 3D.  They had to settle for releasing mid range models with an unbeatable price/quality ratio.

The Radeon HD 4870 is a high end card and the Radeon HD 3870’s replacement.  ATI’s desire is to offer a mono-chip card that is capable of rivaling with Nvidia’s high end.  From a design point of view, the two models are similar.  Our only regret is that they didn’t opt for 1 GB of memory like NVIDIA’s GTX 280.  Instead there is 512 MB (or even less) although some manufacturers offer 1 GB models.  The length of this card is acceptable at 24cm while the radiator is a double slot type.
 
In terms of synthetic performances, here is the behavior of this card depending on the size of the LCD screen on different games we tested and then in the reading of two HD movies in Blu-ray format:



A more into depth look: speeds, HD movies, power consumption, noise levels…

One thing that jumps to our attention with this model is that it’s supposed to be on the top shelf although it ‘’only’’ has 512 MB of memory.  This is surprising in the sense that NVIDIA now offers 1 GB on its GTX 280 and 896 MB with the GTX 260 which are both in the high end segment.  In the same line of thinking, the memory bus is limited to 256 bits versus 512 bits and 448 bits for NVIDIA. Schematically, it means that the highway planned for the transmission of texture data is much narrower for ATI.  We can therefore expect performances to be held back in high resolution.  To limit this, and they are the first manufacturer to do so, they use GDDR5 memory.  It enables increasing the memory bandwidth to attain 107 GB/s or a little more than the GTX 260’s 104 GB/s.

In practice, we get the impression that the optimization made on memory is right on target because the card enables comfortable playability with the latest 3D games (except Crysis), including on large diagonal sizes when activating texture filters (see box).  We then find ourselves at the same level of performances as a Radeon HD 3870 X2 (which you may recall uses two chips from ATI’s high end) and even surpassing the GeForce 9800 GTX 512 MB in some cases.  It’s therefore a big improvement especially now that the problem of abnormally low performances when using texture filters was resolved at the same time.  It isn’t enough, however, to dethrone the GeForce GTX 280 which is still far ahead in our tests.  Nevertheless, depending on the game and particular graphic scene, the HD 4870 sometimes manages to come close to NVIDIA’s latest creation.



As for HD decompression, there is nothing to add except that the AVIVO engine is still very good whether it’s with VC-1 or H.264.  This brings us to the card’s weaknesses, the first being heat levels. Like for the HD 4850, its smaller sibling, the 4870’s is maintained at around 80°.  It’s a rather high temperature and the radiator fan tends to « yoyo » when the card is found in a poorly ventilated casing, varying from silent to audible every 10 seconds.  On the other hand, a well ventilated casing can help to remedy this problem.  For this reason, you may have guessed that power consumption in 2D is higher than the previous generation at  180W for the entire configuration at rest or 25W more than the GTX 280.

Information on the card tested:

Sapphire put their Radeon HD 4870 512 MB at our disposal. It’s a standard model with the reference design, cooling system and frequencies.  In the package, besides the different video cables and DVI adaptors, we find a USB 2 GB with the brand’s logo as well as Power DVD 7 (audio version 5.1), DVD Suite and 3DMark06.