AMD Radeon HD 3800: ATI Strikes Back

Triple And Quad CrossFire, Specifications

CrossFire Shifts To Third And Forth Gear... Well Soon

Whereas for NVIDIA, the quad-SLI failure was so overwhelming that it actually never existed (some new developments are coming soon...), AMD hence takes the opportunity to steal the Chameleon's thunder, if we can actually call it that, by introducing the possibility to group 2, but also 3 and 4 identical cards with its Radeon HD 3800. In reality, this is just an announcement however, since the drivers shouldn't truly be ready until next month at best, AMD itself talking about an actual maximal improvement of only x3.3 with 4 cards. The Global Illumination demo that we were able to see with the manufacturer was indeed working on such a machine with beta drivers and was clearly not stable.

Quad Crossfire, only at AMD

Note the absence of direct connection between cards 1 and 3, 2 and 4 and 1 and 4

This possibility will require another chipset, the AMD 790FX, which we'll go over in more detail after the Phenom launch. The next drivers should also introduce the Overdrive for Crossfire systems, meaning the ability to increase every card's clock at the same time.


In the end, how does one explain this decline in number of transistors? Probably by the presence, in the R600, of disabled redundant units, meant to improve yields, considering the size and process of the chip. It's also probable that certain features appearing with the RV670 were already present on the R600, but disabled because of bugs.

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Mains cards specification
GPUHD 3850HD 38708800 GT
GPU's Clock670 MHz775 MHz600 MHz
Shaders' Clock670 MHz775 MHz1500 MHz
Memory's Clock833 MHz1125 MHz900 MHz
Width of the Memory Bus256 bits256 bits256 bits
Memory Quantity256 Mo512 Mo512/256 Mo
Number of Pixels/Vertex Pipelines(80)(80)(28)
Number of Texturing Units161656
Number of ROP161616
Throughput429 GFlops496 GFlops336 GFlops
Memory Bandwidth53.3 GB/s72 GB/s57.6 GB/s
Number of Transistors666 million666 million754 million
Die's surface196 mm²196 mm²324 mm²
Supported Shader Model4.14.14.0

Good news in any case, using a 55 nm process enables AMD to own a chip that has a surface two times inferior than that of the R600, and more importantly, significantly smaller than the G92 by at least 41%. A real weapon in the oh-so-important price war fought between the market's two manufacturers, even if, once more, we need to take into account AMD's yields, which are probably worse at 55 nm than those of NVIDIA's G92.