AMD ATI Radeon HD 4870 X2

The Radeon HD 4870 X2 is here in final form, sporting a new BIOS and brand new drivers, this video card is poised to take the performance crown. We will evaluate real-world gameplay experiences in Crysis, Age of Conan, Call of Duty 4 and Grid concentrating on high-resolution gaming with AA and providing A2A tests.

Introduction

Back on July 14th, 2008 we had the opportunity to preview two pre-production Radeon HD 4870 X2 video cards. This early hardware showed great promise of delivering a lofty high-end gameplay experience. We were most shocked to find that previously unreachable levels of antialiasing were playable at resolutions of 1920x1200 and 2560x1600.

In fact, this evolution in antialiasing performance prompted us to do further testing with the Radeon HD 4800 series to find out what AMDآ’s CFAA modes were all about. We have been greatly impressed by AMDآ’s current level of AA performance in games, and now that we have final production hardware we can use these CFAA modes at high resolutions and see how it handles AA and show you what you can expect.

Specifications

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In the preview, the specifications were already given for the Radeon HD 4870 X2. These specifications remain the same for the final production video card, the only difference is that a new BIOS is being used and new drivers are now released. The Radeon HD 4870 X2 has an MSRP of $549 with the street price bumping between $549 and $559.

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The Radeon HD 4870 X2 is a single PCB video card, but there are two GPUs on board hardwired with a proprietary interconnect. This interconnect bridge is a PCIe Gen2 capable chip providing bi-directional x16 lanes between both GPUs. AMD claims up to 80% scaling with both GPUs so efficiency is still an issue with this multi-GPU configuration.

The interconnect in the Radeon HD 4870 X2 has been improved over the previous Radeon HD 3870 X2. In the previous generation the total interconnect bandwidth was 6.8GB/sec and now it is 21.8GB/sec allowing over 3X greater bandwidth between the GPUs. There is also a piece of technology dubbed Sideport, that provides additional bandwidth between the GPUs, however that technology is currently disabled. There is no word if AMD will ever enable this between the GPUs.

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The core clock speed is 750MHz for each GPU, and the memory uses GDDR5 modules at 3.6GHz per GPU. There is also a 1GB framebuffer per GPU, not 2GB as the slide might have you understand. The total memory capacity on this video card is indeed 2GB, but each GPU can only access 1GB of that since the framebuffer is duplicated due to the nature of CrossFire. Total board power is rated at 286W. Keep in mind when looking at specification sheets that AMD likes to آ“doubleآ” the amounts of things like stream processors and memory, since there are two GPUs on board. Of course, each GPU itself still has 800 stream processors..


AMD ATI Radeon HD 4870 X2

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The final form of the Radeon HD 4870 X2 hasnآ’t changed from the video card we previewed. There is a large heatsink covering both GPUs and a fan shroud covering the entire length of the video card. The fan intakes air and exhausts it out the back of the computer. From the back you can see where the two GPUs are located on the board.

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A 6-pin auxiliary and 8-pin auxiliary power connector is required for proper operation of this video card. CrossFireX is also supported with one bridge connector to allow two Radeon HD 4870 X2آ’s to operate together to improve performance further.