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Sapphire HD 5970 dual GPU Radeon lands in our lab

by on26 November 2009



Review: All hail the new performance king





AMD has launched most of its Evergreen family cards, including the toughest of the lot – the Radeon HD 5970. Evergreen is AMD's DirectX 11 supporting family of graphics cards, with which AMD returned to the winning ways, at least in the field of graphics. Apart form the speed and the muscle, Evergreen brings a couple of other things to the table, most notably Eyefinity, which is support for more than two monitors on one card. In case you don't recall, about a month ago we talked about Radeon HD 5870 graphics card, which is the first Evergreen card to hit the market and still is the single-GPU king of the market. A few slower Evergreen single-GPU offerings followed – the HD 5850, HD 5770, HD 5750, but enthusiasts have anxiously waited on AMD's dual GPU card codenamed Hemlock, a.k.a. Radeon HD 5970.

Today we have Radeon HD 5970, currently the world's fastest graphics card, and we've received it from our friends in Sapphire, unique and one of the most famous AMD partners. Radeon 5970 comes with two GPUs, and we've come to expect such solutions when maximum muscle is the aim of the game.

Unlike traditional Crossfire, where two single-Gpu cards are in separate PCI-Express slots, AMD's dual-GPU card can at a glance be compared to one single-GPU card. Don't be fooled by the looks though, as Hemlock's hood hides two GPUs and one on-board PLX bridge chip (PEX 8647 switch commanding 48 PCI-Lanes), which is in charge of internal GPU communication. In theory, this should allow for matching the card's performance to the performance of two single-GPU cards in Crossfire.

Physically comparing the HD 5970 with other graphics cards reveals that the new dual-GPU Radeon measuring 31cm in length, is easily the longest graphics card on the market. Of course, dual-GPU cards present somewhat of a cooling challenge, and thus they usually arrive with hefty cooling solutions. On the other hand, the size has been compensated with cooling efficiency and silent operation, which is commendable. AMD opted on using Vapor Chamber technology, so those who feared less than optimum cooling solutions can breathe a sigh of relief. 

If you're wondering whether Radeon HD 5970 will fit in your case, there is a simple test – take an A4 sheet of paper and try to put it where the graphics card should be located, but bear in mind that it will take 1cm more than the A4 sheet measures. Of course, those who await on HD 5970 will surely have plenty of room to welcome this €500+ beast.

Interestingly enough, the operating clocks on the HD 5970 are lower than on Radeon HD 5870 cards, despite the fact that they're based on the same, Cypress core. The HD 5970's clocks actually match those on the HD 5850. The HD 5970's core runs at 725MHz, as opposed to the HD 5870's 850MHz. Hemlock's GDDR5 is slower as well and it runs at 1000MHz (4000MHz effectively), compared to the HD 5870s 1200MHz (4800MHz effectively). The reason was to keep the card within the PCIe 2.0 specification which states at most 300W at load. Of course, Sapphire had the final say by pushing the clocks further, but this time only by 10MHz. 

We must admit that up until the launch day, we expected the card to come with the X2 suffix, which was the case with the previous generation's HD 4870 X2. However, as you can see for yourself, lower clocks do not allow for such a name.

Radeon HD 5970 offers 1600 stream processors per Cypress core, 80 texture units (which can address and texture one pixel per clock) as well as 32 ROP units per core. The GPU is built in 40nm and measures 334mm square. The card has a total of 2GB of GDDR5 memory at its disposal, where each GPU has its own 1GB on a 256-bit memory interface. 

Compared to the previous generation, improvements are obvious and you'll notice that almost everything got doubled up. 800 shaders on the HD 4890 became 1600 on the HD 5870, courtesy of the added batch of transistors. The Cypress GPU features complex architecture with 2.15 billion transistors, as opposed to 959 million on the HD 4890. The ROPs also got an overhaul, and have been doubled from the HD 4870's 32 to HD 5870's 32. The same goes for texture units as well as computing power which jumped from 1.2 TFLOPs to 2.72 TFLOPs. 

An important piece of the puzzle is that despite the doubled performance, consumption didn't suffer much. We already said that the HD 5970 consumes up to 294W, which is nice if you consider that one HD 5870 consumes 188W or that HD 4870 draws up to 160W. AMD finally addressed idle consumption, and the company claims HD 5870 will draw only 27W whereas the HD 5970 will draw 51W when idle.

Despite the size, the HD 5970 is an attractive graphics card. The picture below shows that Sapphire stuck to using reference cooling.


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Last modified on 26 November 2009
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