ATI Radeon HD 4870 X2 - AMD Back On Top
The Radeon HD 4800 series didn't overwhelm NVIDIA's GTX 200 series with raw performance. In fact, the GeForce GTX 280 and 9800 GX2 were more powerful than the Radeon HD 4870. The Radeon HD 4800 series cards, however, were still excellent cards and they were offered at extremely competitive prices, which put significant pressure on NVIDA. At the time of their launch, the Radeon HD 4850 and Radeon HD 4870 were both less expensive and more powerful than the GeForce 9800 GTX and GeForce GTX 260, respectively. Since then, NVIDIA has reacted with a quick round of price cuts.
While enthusiasts were contemplating the purchase of a new Radeon or GeForce, AMD then planted another seed and released some concrete details regarding the Radeon HD 4870 X2, as if to say, "Yeah, we've got you covered at the $300 price point and a new, ultra powerful behemoth is coming real soon too. Maybe you should hold onto your upgrade money for a bit?"
That behemoth is the Radeon HD 4870 X2. As its name suggests, the card features two RV770 GPUs running in tandem, for what is effectively a Radeon HD 4870 CrossFire configuration on a single PCB. Other than its pair of GPUs, however, the Radeon HD 4870 X2 has a few more differentiating factors we'll need to tell you about. Read on for the full scoop...
ATI Radeon HD 4870 X2 Cards (Codename R700)
ATI PowerPlay
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ATI Avivo HD Video and Display Platform
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As the above list of specifications and features show, the new Radeon HD 4870 X2 has the exact same features as the Radeon HD 4870; it just has two GPUs. Like the other members of the Radeon HD 4800 series, the Radeon HD 4870 X2 offers DX10.1 and Shader Model 4.1 support, the GPUs are manufactured on TSMC's 55nm process node, and both support ATI's CrossFireX multi-GPU technology.
Because we've covered essentially all of the shared features of the Radeon HD 4800 and 3800 series cards before, we won't be going into them in depth again here. However, we would recommend taking a look at a few recent articles to brush up on the tech if you're so inclined.
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AMD acheived this feat by increasing the population of the architecture's SP count from 320 on the older RV670 to a 800 on the RV770. AA and Z/Stencil performance were enhanced as well, and the number of texture units was increased from 16 to 40. The 800 stream processing units are grouped in a new SIMD core layout, and the texture units, ROPs, and cache have been restructured to minimize transistor count, while also increasing performance. With the RV770, AMD claims that the SPs in the GPU offer 40% more performance per square millimeter that the previous generation, and that more aggressive clock gating offers improved performance per watt as well. Likewise, the newly streamlined design of the RV770 texture units reportedly offer 70% more performance per square mm with double the texture cache bandwidth and large increases in 32- and 64-bit filter rates.
