Introduction

The day we've been waiting for since the past couple of months has finally arrived. AMD, which pioneered DirectX 11 compliant PC consumer graphics, is out with its second-generation Radeon HD 6800 DirectX 11 architecture, codenamed Northern Islands. The company has enjoyed a 6 month head-start into the race for DirectX 11 graphics hardware market dominance, which also reflected in both growth of market-share, and domination in sales. The time passed by also allowed AMD to refine and fine-tune its architecture to better suit the existing 40 nm silicon fabrication process, by promising to churn out higher performance per Watt and performance per mm² of die-area (plays an important role in product pricing), compared to the previous-generation Evergreen architecture.

The architecture of the Radeon HD 6870 also refines and expands on the product's feature-set, giving the GPU an even bigger role to play in today's PC than simply rendering 3D graphics: that's accelerating smooth and crystal-clear high-definition video, and getting into CPU territory, by number-crunching for applications at a much more parallel scale than multicore processors.

The HD 6870 and HD 6850 products also mark a fundamental shift in AMD's approach to the market. Until now, the Radeon HD x800 series (such as HD 3800 series, HD 4800 series, and HD 5800 series) is regarded as that class of SKUs that give you the highest single-GPU performance possible for the prevalent architecture. But now, AMD has restructured its nomenclature in a big way.

AMD bought ATI Technology back in 2006, yet it allowed ATI to remain as a brand name, since it has quite some market value to lead the graphics products, as its parent company moved through a rough patch on many fronts. Later, in a more stable environment, with two successive GPU series, the Radeon HD 4000 series and Radeon HD 5000 series, doing very well in the market, the company was able to gradually create a situation where "Radeon" became a bigger brand name than "ATI", at least that's what AMD argues, and hence has done away with "ATI" completely. So say hello to the first AMD-branded graphics processor

Since the time of the Radeon 9600 XT and GeForce FX 5700 series, there has always been a $250-ish price-point which was very rigid, and held the reins of the "mid-range". Later, with increase in competitiveness between ATI and NVIDIA; product development cycle sped up, leading to a broadening of that mid-range spectrum, which then took over as a vast group of price-points starting from $100, all the way up to $250.

Fast forward to Radeon HD 4000 series, AMD noticed quite some vacuum to fill between its $90 Radeon HD 4670, and the Radeon HD 4850, which at the former's launch was priced at $100, twice as much, there really was scope for something in the between since GeForce 9800 GT was having a party. Hence it created the Radeon HD 4700 series, which incidentally is also the first 40 nm GPU. The Radeon HD 5700 series kept up the legacy, and offered performance SKUs at $199 and $149 price-points. The GeForce GTX 460 from NVIDIA created a big aberration. It targeted $199 and $229 price points; while delivering performance levels comparable to some high-end SKUs priced around $299, also cannibalizing the GeForce GTX 465.

AMD was finding it hard to compete with NVIDIA because there are many customers looking for something that lasts for a while, with $200-$230 to spend, to whom, even a dirt-cheap Radeon HD 5700 series GPU was looking like a very myopic, short-term investment. It is this chunk of the market that went on to be labeled as the "gamer's sweet-spot", Radeon HD 5830 was a blot in AMD's HD 5000 series, it couldn't be sold for lesser than a certain amount, and didn't have much more performance than the HD 5770. This expedited development of the Northern Islands architecture, and AMD designed the 40 nm "RV940" Barts GPU.

When it came to light that Barts, oversimplistically a successor to the Juniper GPU (which makes up the Radeon HD 5700 series), is going to be branded under the HD 6850/6870 series, it created quite some drama; with some users claiming it to be very gimmicky of AMD to release a series that isn't much of an upgrade option for existing users of HD 5800 series GPUs. That's not the case, because AMD made it adequately public through the press, its reasoning behind using the HD 6800 series as the "gamer's sweet spot" series, and consolidating all higher-end SKUs into the Radeon HD 6900 series, slated for next month. Besides, it's not like AMD is asking Radeon HD 5800 series kind of prices for the cards released today. The main design ideology behind the HD 6870, as AMD put it, is to give you Radeon HD 5800 series performance at sweet-spot prices.

The Radeon HD 6870 graphics card from HIS we're reviewing today sticks to the reference design from AMD. It uses a premium PCB as well as premium blower-type cooling assembly designed by AMD. The card also sticks to reference AMD clock speeds of 900 MHz core and 1050 MHz memory (4200 MHz GDDR5 effective). Display connectors on this card include two DVI, one HDMI 1.4a, and two mini-DisplayPort 1.2 connectors.

Also check out our other HD 6800 reviews today:

ASUS Radeon HD 6850 Direct Cu
HIS Radeon HD 6850
AMD Radeon HD 6870 CrossFire
AMD Radeon HD 6850 CrossFire

Architecture

Barts, named after the Saint Barthélemy island in the Caribbean, is a performance-segment GPU. It is built on the 40 nm silicon fabrication process at TSMC, Taiwan. Since it is essentially a DirectX 11 generation GPU, most of the components are the same as on the Radeon HD 5000, albeit with a lot of restructuring. The SIMD processing area, like on the Cypress, is branched into two blocks, because there are way too many SIMD units. While Cypress had a single Ultra-Threaded Dispatch Processor component that semaphored instructions and data between the two clusters, with Barts, AMD gave each cluster its own dispatch processor, instruction and constant caches, thus increasing the parallelism. Each cluster holds 7 SIMD engines, with 80 stream processors, each. The computational power of Barts in its Radeon HD 6870 avatar, hence, is over 2 TFLOPS.



There are 56 texture units (TMUs) on Barts, all enabled on the HD 6870, 48 enabled on the HD 6850. With a 256-bit wide GDDR5 memory interface, there are 32 raster operations processors (ROPs). AMD also addressed the one shortcoming of the Evergreen architecture which NVIDIA took advantage of: tessellation performance. Northern Islands GPUs carry a second generation tessellation unit that is both redesigned, and is backed by a new adaptive tessellation algorithm at the driver level. Together, up to 100% increase in tessellation performance is advertised by AMD.



There is a redesigned video acceleration component, the 3rd generation Unified Video Decoder (UVD 3.0), which provides GPU acceleration for Blu-ray 3D and DivX high-definition video formats, and six display controllers offering six TMDS links. This lets users connect up to six displays to as independent display heads, or span display heads across multiple physical displays using the Eyefinity technology. The new HDMI 1.4a connector standard is made use of, which gives you support for stereoscopic 3D standards such as Blu-ray 3D, the two mini-DisplayPort 1.2 connectors support Multi-Stream technology that let you daisy-chain 3 physical displays per connector, letting you wrap up a 6-display Eyefinity array using just those two connectors.

Packaging

We have seen the tall HIS package on other products before. The design with black background and colorful highlights looks quite stylish in my opinion. A bit more product highlights on the front and back would have been nice.

Contents

You will receive:

• Graphics card
• Driver CD + Documentation
• DVI adapter
• CrossFire Bridge
• 2x PCI-Express power adapter