AMD Radeon HD 6870 & HD 6850 Video Card Review

AMD is launching its new mainstream performance lineup, the Radeon HD 6800 series. The 6800 cards will offer much more performance at the $179 to $239 price range. We compare the new Radeon HD 6870 and Radeon HD 6850 with AMD and NVIDIA cards and find out which delivers the best gameplay experience and value.

Introduction

Over one year ago, AMD launched the first DirectX 11 GPU known as the ATI Radeon HD 5870 to the market, before Windows 7 even shipped. Over one year ago AMD debuted Eyefinity, improving upon the way gamers enjoy their games. Eyefinity was a huge advantage to the gameplay experience, and instead of just making faster GPUs, which we get in every generation, Eyefinity actually improved the gameplay experience. Now, over one year later, AMD is releasing their next generation of GPUs. AMD is ready to release its mid-level performance GPUs now, and a month from now, its high-end enthusiast "Cayman" GPUs.

There will be no less than four video cards released by Thanksgiving from AMD, ranging from the high-end to the performance user. Today, we are going to talk about the GPU codenamed "Barts." This is AMD’s performance range of products known as the Radeon HD 6800 series. Think of Barts like this: Barts is a GPU with Radeon HD 5800-like performance, at a lower price. That is a general description, but really there are architectural improvements with Barts that should give you a bit more performance, but with less power, a smaller die, and a cheaper price.

Confusing Name Change

You are going to have to get used to a different naming scheme with AMD video cards. Going forward the previous 5700 series will be AMD's "low end" series of GPU. The 6800 series we are seeing here today will be the new "mid-level" GPU series. Later this year we will see a 6900 series of GPUs that will represent the high end or enthusiast level cards. Seeing the 5700 series stay intact is somewhat of a testament to the ability of the GPUs.

The 6900 series will have a superset of features compared to the 6800 series. This means that there will be features and architecture differences between 6900 and 6800 series. This allows AMD to take more chances on the high-end enthusiast class GPUs and architecture things different, to really step up performance that enthusiasts demand. So, just to restate, the new 6800 series will offer performance of the 5800 series, at a lower price, with lower power, and a smaller chip.


Specifications

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There will be a Radeon HD 6850 targeted at the $179 price point, and a Radeon HD 6870 targeted at the $239 price point. These two cards replace the current 5800 series. This pricing structure puts the 6850 squarely in competition with the GeForce GTX 460 even after the price reductions we saw earlier today.

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All Barts GPUs are produced with 40nm process. The AMD Radeon HD 6870 will have 1120 Stream Processors at 900MHz. There will be 1GB of GDDR5 at 4.2GHz on a 256-bit bus. There are 32 ROPs and 56 Texture units. The die size is less than that of the Radeon HD 5850 GPU and there are even less transistors. Yet, with this reduction in die size, transistor count and Stream Processors, the Radeon HD 6870 should perform faster than the Radeon HD 5850 thanks to architecture improvements. Max load board power is 151W and idle is 19W, an improvement in idle Wattage compared to 5850, and matching the 5850 for load Wattage. This card requires two 6-pin power connectors. There will be 2x DVI ports plus 2X mini-DisplayPorts which are DP version 1.2 and one HDMI port.

The AMD Radeon HD 6850 has 960 Stream Processors at 775MHz. There is 1GB of GDDR5 at 4GHz on a 256-bit bus. There are also 32 ROPs and 128 Z/Stencil ROPs just like the Radeon HD 6870 and subsequently the 5850 and 5870 as well. Max load board power is 127W and idles at 19W just like the 6870. This video card only requires one single 6-pin power connector. This video card has the same output connections as the 6870.

Architecture Improvements

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AMD has not just slapped last generation Radeon HD 5800 GPU specifications into a smaller package, AMD has evolved and refined the architecture for the Radeon HD 6800 series. AMD was able to squeeze more performance out of this architecture while also reducing transistor count and die size. This allows AMD to get more than 5850 performance out of the 6870 with less. This will be AMD’s 7th generation Tessellation engine, if you count back to the Radeon 8500’s TruForm hardware. AMD claims they have improved thread management and buffering in this generation, which should provide better Tessellation performance clock-for-clock with the 5800 series.

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There are some new image quality features in play, which we think you guys are going to like. The one we are interested in is Morphological AA. We are interested in this new AA technique for the sole reason that we hate shader aliasing in games. Now that games are using more and more shader effects, there is aliasing caused by these effects, such as specular lighting and shadowing. Morphological AA will improve the entire scene since it is a full-scene post-process effect generated via DirectCompute by the Stream Processors. This means it will add a layer of performance penalties, but how much is uncertain yet until we fully test it. The great thing about this new technique is that it will work in every application, no special code is needed, we just simply need to enable it in the control panel.

Unfortunately, the driver initially sent to us by AMD does not support the Morphological AA feature, so we cannot test it in this evaluation. A new driver was sent to us a day ago that does support MAA, but we haven’t had the time to look at the feature yet. A follow-up will come where we look at this image quality feature.

AMD has improved filtering again, which many thought was already close to perfect. We certainly haven’t seen any issues with filtering in any games recently. At any rate, AMD did not sit still and has improved filtering between texture levels with this latest generation.

Video Card Pictures

Radeon HD 6870

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Radeon HD 6850

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The AMD Radeon HD 6870 requires two 6-pin power connectors, and there is one CrossFireX bridge connector. The Radeon HD 6800 series (6870 and 6850) only support dual-GPU CrossFireX. That is, you can only connect two of them for added performance. The reason for this is because of their targeted price point, AMD just doesn’t see gamers at this price point pushing these video cards to triple-GPU configurations, and we agree. The reduction down to only one CrossFireX bridge connector has also reduced board costs, which is always a good thing.

The AMD Radeon HD 6850 only requires one 6-pin power connector. It is also much shorter. The AMD Radeon HD 6870 measures in at 9.5 inches, which is shorter than a Radeon HD 5850. The AMD Radeon HD 6850 measures 9 inches long which is 1 inch longer than an HD 5770. Both video cards have two mini-DisplayPort version 1.2 connectors. This is important because of the new Eyefinity features supported allowing daisy chaining displays and using a specialized hub to output multiple displays. HDMI version 1.4a is supported in hardware on both video cards and you receive the usual two dual-link DVI connectors.

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