Chicago (IL) – Next month will be more important for AMD’s graphics division than any other month of this year: The company is set to release the (RV770) 4800-series of graphics cards, including the models 4850, 4870 and 4870 X2. While the launch is still very much a secret, TG Daily was able to receive details and the specifications of the new cards – which will put ATI back into the ring with Nvidia.

The product launch will be significant not just because of the availability of chips, but also because of the fact that AMD/ATI is returning to a true six-month refresh cycle of its graphics products. Looking back, the 2900/3800 series was not really a six-month refresh, since the 2900XT was eight months late. The Radeon 3800 series was launched in November of 2007 and since the Radeon 4800 is pretty much set for a May 2008 launch (cards went into production in March), the ATI team has returned to its traditional cycle. There is a good chance that the acquisition troubles have been digested and new products will be surfacing in a more predictable fashion from now on.


Specifications: 480 stream processors, 800+ million transistors

Let’s have a look at the general specifications of the Radeon 4800 series, which is based on the RV770 graphics processor. The new GPU has 480 stream processors or shader units (96+384), 32 Texture units (up from 16), 16 ROP (same as 2900/3800), a 256-bit memory controller and native GDDR3/4/5 support (expect GDDR3 and GDDR5 memory versions of RV770 cards).

The transistor count has jumped from 666 million in the RV670 to more than 800 million transistors in the RV770.

The manufacturing process has been carried over: TSMC is producing the GPUs in 55 nm (the process itself is called 55GC).

The Radeon 3800 series had a serious flaw called texture low fill-rate, which was addressed by ATI with an increased number of TMUs (Texture Memory Unit) from 16 to 32. The specifications indicate that 16 TMUs can address 80 textures on the fly, which means that 32 units should be able to fetch 160 in the RV770: This should allow the new GPU to catch up with Nvidia’s G92 design. However, the G92 has 64 TMUs that were enabled gradually (some SKUs shipped with 56), resulting in a fill-rate performance that beat the original 8800GTX and Ultra models.  

ATI’s RV770 will be rated at a fill rate of 20.8-27.2 GTexel/s (excluding X2 version), which is on the lower end of the GeForce 9 series (9600 GT: 20.8; 9800 GTX: 43.2 9800 GX2: 76.8).

New for the 4800 series is AMD’s decision to split the clock of the GPU and shaders, following a move that Nvidia made with the GeForce 8800: Back then, the shaders were clocked at 1.35 GHz, while the rest of the chip ticked at 575 MHz.


Read on the next page: GPU and memory clock speeds, Pricing