Introduction

Next month AMD will introduce their latest family of graphics chips, called “Southern Islands,” based on a completely new architecture and supporting the new PCI Express 3.0 protocol. The first model to be released will be the most high-end model, the Radeon HD 7970, codename “Tahiti,” which will cost USD 550. Let’s check its performance.

The Radeon HD 7970 has 2,048 processors (“cores”), works at 925 MHz and accesses its 3 GB of GDDR5 memory at 5.5 GHz through a 384-bit interface, creating a bandwidth of 264 GB/s. This GPU is the first DirectX 11.1, the first PCI Express 3.0, and the first 28 nm product to arrive on the market.

The new architecture used by the “Southern Islands” family, which is called “Graphics Core Next” or simply “GCN,” makes it easier to run regular programs on the GPU compared to AMD’s previous generation of GPUs. Therefore, you should expect to see higher performance on applications that use the GPU for speed-up processing. Of course, we will test this feature in this review.

There are several new features available on the Radeon HD 7970. The first one is called “Power Tune,” which is an automatic overclocking feature similar to Intel’s Turbo Boost, which increases the clock of the graphics chip if there is room in its TDP (Thermal Design Power). This video card can consume up to 250 W, so if the GPU is dissipating, say, 100 W, it knows it can have its clock increased for higher performance. According to AMD, the GPU can increase its clock rate up to 30 percent.

Speaking of oveclocking, according to AMD, the Radeon HD 7970 has a lot of headroom for overclocking; the GPU can easily be set to work at 1 GHz or more and the memory at 6.5 GHz or more.

The second new feature is called “Zero Core,” which completely turns off the GPU and the video card fan when the video monitor is commanded to turn off by the operating system after the computer is idle for a long time. The video card consumption during this stage is only 3 W. According to AMD, the Radeon HD 6970 consumes around 20 W when in long idle mode. This feature also works in CrossFireX mode, completely turning off the extra video cards. The Radeon HD 7970 is expected to consume around 15 W when idle, showing a static image.

Another new feature is an integrated video encoder called VCE (Video Codec Engine), which provides hardware acceleration for encoding H.264 videos. The video decoder, called UVD (Unified Video Decoder), was expanded to include support for hardware-based MPEG4 and DivX decoding.

In the table below, we compare the main specifications of the video cards included in our review. The prices listed below do not include rebates. Prices were researched at Newegg.com on the day we published this review, except for the Radeon HD 7970, which is the price advertised by AMD.

Video Card	Core Clock	Shader Clock	Memory Clock (Effective)	Memory Interface	Memory Transfer Rate	Memory	Shaders	DirectX	Price
Radeon HD 7970	925 MHz	925 MHz	5.5 GHz	384-bit	264 GB/s	3 GB GDDR5	2,048	11.1	USD 550
Radeon HD 6970	880 MHz	880 MHz	5.5 GHz	256-bit	176 GB/s	2 GB GDDR5	1,536	11	USD 350
GeForce GTX 580	772 MHz	1,544 MHz	4,008 MHz	384-bit	192.4 GB/s	1.5 GB GDDR5	512	11	USD 500

NVIDIA offers a 3 GB version of the GeForce GTX 580 between USD 530 and USD 590, which is the true competitor against the Radeon HD 7970. However, we didn’t have one to include in our comparison.

You can compare the specs of these video cards with other video cards by taking a look at our “AMD ATI Chips Comparison Table” and “NVIDIA Chips Comparison Table” tutorials.

Today, only the LGA2011 Core i7 processors (“Sandy Bridge-E”) have a PCI Express 3.0 controller. Therefore, we tested the three video cards using a Core i7-3960X processor on a motherboard based on the Intel X79 chipset. Then we tested the Radeon HD 7970 again with a Core i7-980X processor on a motherboard based on the Intel X58 chipset, to see if the use of a PCI Express 2.0 bus would make any difference in performance.

Now let’s take a complete look at the AMD Radeon HD 7970.

The AMD Radeon HD 7970

Below we have an overall look at the AMD Radeon HD 7970 reference model. It requires one six-pin and one eight-pin auxiliary power connectors.

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Figure 1: AMD Radeon HD 7970

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Figure 2: AMD Radeon HD 7970

One of the highlights of this video card is the possibility of connecting up to six video monitors at the same time, which is achieved by using a DisplayPort hub or a DisplayPort monitor that provides daisy-chaining capability. The card provides one DVI-D, one HDMI, and two mini DisplayPort connectors. According to AMD, Radeon HD 7970 video cards will come with a single-link active DisplayPort-to-DVI adapter, so you will have two DVI-D connectors available.

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Figure 3: Video connectors

The AMD Radeon HD 7970 (Cont’d)

The Radeon HD 7970 uses a new cooler, based on vapor chamber technology, which is similar to the technology used by heatpipes. AMD says you can’t remove the GPU cooler, because the performance won’t be the same after you put the video card back together. That is why we didn’t disassemble this video card. Figure 4 was provided by AMD. According to the manufacturer, the fan is also new, providing higher air flow at a lower speed.

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Figure 4: Video card cooler

The reviewed video card has two BIOS chips, selectable through a switch. This way you can select between the default configuration or an overclocked configuration, which you created and saved “permanently” to the second BIOS chip.

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Figure 5: BIOS switch

Before seeing the performance results, let’s recap the main features of this video card.

Main Specifications

The main specifications for the AMD Radeon HD 7970 reference model include:

• Graphics chip: Radeon HD 7970 running at 925 MHz
• Memory: 3 GB GDDR5 memory (384-bit interface) running at 5.5 GHz QDR
• Bus type: PCI Express 3.0 x16
• Video Connectors: One DVI-D, one HDMI, and two mini DisplayPort
• Video Capture (VIVO): No
• Cables and adapters that come with this board: One active, single-link mini DisplayPort-to-DVI-D
• Number of CDs/DVDs that come with this board: NA
• Games included: NA
• Programs included: NA
• More information: http://www.amd.com
• MSRP in the US: USD 550.00

How We Tested

During our benchmarking sessions, we used the configuration listed below. Between our benchmarking sessions, the only variable was the video card being tested.

Hardware Configuration (PCI Express 3.0 Tests)

• CPU: Core i7-3960X (3.3 GHz)
• Motherboard: Intel DX79SI (0380 BIOS)

Hardware Configuration (PCI Express 2.0 Tests)

• CPU: Core i7-980X (3.33 GHz)
• Motherboard: MSI Big Bang XPower (1.6 BIOS)

Hardware Configuration (Both Platforms)

• Memories: 16 GB DDR3-2133/PC3-1700, four G.Skill Ripjaws Z F3-17000CL9Q-16GBBZH memory modules
• Hard disk drive: Western Digital VelociRaptor WD3000GLFS (300 GB, SATA-300, 10,000 rpm, 16 MB cache)
• Video monitor: Samsung SyncMaster 305T (30” LCD, 2560x1600)
• Power Supply: Antec TruePower New 750 W
• CPU Cooler: Intel Liquid Cooling

Software Configuration

• Windows 7 Ultimate 64-bit
• Video resolution: 2560x1600 @ 60 Hz

Driver Versions

• AMD video driver version (Radeon HD 6970): Catalyst 11.12
• AMD video driver version (Radeon HD 7970): 8.921.2.0
• NVIDIA video driver version: 285.62
• Intel Inf driver version (X79): 9.2.3.1022
• Intel Inf driver version (X58): 9.1.2.1008

Software Used

• 3DMark 11 Professional 1.0.3
• Aliens vs. Predator + Benchmark Tool
• Battlefield 3
• Deus Ex: Human Revolution
• DiRT3
• Far Cry 2 – Patch 1.03
• Media Espresso 6.5
• StarCraft II: Wings of Liberty - Patch 1.3.5

Error Margin

We adopted a 3% error margin. Thus, differences below 3% cannot be considered relevant. In other words, products with a performance difference below 3% should be considered as having similar performance.

StarCraft II: Wings of Liberty

StarCraft II: Wings of Liberty is a very popular DirectX 9 game that was released in 2010. Though this game uses an old version of DirectX, the number of textures that can be represented on one screen can push most of the top-end graphics cards to their limits. StarCraft II: Wings of Liberty uses its own physics engine that is bound to the CPU and thus does not benefit from PhysX.

We tested this game at 1920x1200 and 2560x1600. The quality of the game was set to the “extreme” preset. We then used FRAPS to collect the frame rate of a replay on the “Unit Testing” custom map. We used a battle between very large armies to stress the video cards.

Starcraft II: Wings of Liberty	1920x1200	Difference
Radeon HD 7970 (PCI-E 3.0)	215.886
Radeon HD 7970 (PCI-E 2.0)	215.875	0%
Radeon HD 6970	201.412	7%
GeForce GTX 580	182.880	18%

Starcraft II: Wings of Liberty	2560x1600	Difference
Radeon HD 7970 (PCI-E 3.0)	174.754
Radeon HD 7970 (PCI-E 2.0)	173.774	1%
Radeon HD 6970	164.431	6%
GeForce GTX 580	161.883	8%

Far Cry 2

Released in 2008, Far Cry 2 is based on a game engine called Dunia, which is DirectX 10. We used the benchmarking utility that comes with this game at 1920x1200 and 2560x1600, setting overall quality to “ultra high,” maximizing all image quality settings, adjusting anti-aliasing to “8x,” and running the “Ranch Long” demo three times. The results below are expressed in frames per second and are an arithmetic average of the three results collected.

FarCry 2	1920x1200	Difference
GeForce GTX 580	105.1	13%
Radeon HD 7970 (PCI-E 2.0)	95.5	2%
Radeon HD 7970 (PCI-E 3.0)	93.4
Radeon HD 6970	87.7	7%

FarCry 2	2560x1600	Difference
GeForce GTX 580	70.8	2%
Radeon HD 7970 (PCI-E 3.0)	69.7
Radeon HD 7970 (PCI-E 2.0)	68.8	1%
Radeon HD 6970	62.1	12%

Aliens vs. Predator

Aliens vs. Predator is a DirectX 11 game that makes full use of tessellation and advanced shadow rendering. We used the Aliens vs. Predator Benchmark Tool developed by Rebellion. This program reads its configuration from a text file. (Our configuration files can be found here.) We ran this program at 1920x1200 and 2560x1600, with texture set at “very high,” shadows set at “medium,” anisotropic filtering set at “8x,” and anti-aliasing set at “2x.”

Aliens vs. Predator	1920x1200	Difference
Radeon HD 7970 (PCI-E 3.0)	66.4
Radeon HD 7970 (PCI-E 2.0)	66.0	1%
Radeon HD 6970	60.1	10%
GeForce GTX 580	52.4	27%

Aliens vs. Predator	2560x1600	Difference
Radeon HD 7970 (PCI-E 2.0)	41.2	0%
Radeon HD 7970 (PCI-E 3.0)	41.0
Radeon HD 6970	38.2	7%
GeForce GTX 580	32.5	26%

DiRT3

DiRT3 is a DirectX 11 game. We measured performance using this game by running a race and then playing it back using FRAPS. We ran this game at 1920x1200 and 2560x1600 with image quality set to “ultra,” with anti-aliasing set at “8xMSAA.”

DiRT3	1920x1200	Difference
Radeon HD 7970 (PCI-E 3.0)	77.24
Radeon HD 7970 (PCI-E 2.0)	76.87	0%
Radeon HD 6970	71.4	8%
GeForce GTX 580	70.43	10%

DiRT3	2560x1600	Difference
Radeon HD 7970 (PCI-E 3.0)	55.51
Radeon HD 7970 (PCI-E 2.0)	55.24	0%
Radeon HD 6970	50.12	11%
GeForce GTX 580	47.58	17%

Deus Ex: Human Revolution

Deus Ex: Human Revolution is another DirectX 11 game. We used the in-game introduction to measure the number of frames per second, using FRAPS. We ran the introduction in two resolutions, 1920x1200 and 2560x1600, maximizing all image quality settings, configuring anti-aliasing as “MLAA Mode” and anisotropic filtering at “16x.”

Deus Ex: Human Revolution	1920x1200	Difference
Radeon HD 7970 (PCI-E 3.0)	202.62
GeForce GTX 580	201.78	0%
Radeon HD 7970 (PCI-E 2.0)	199.78	1%
Radeon HD 6970	184.13	10%

Deus Ex: Human Revolution	2560x1600	Difference
Radeon HD 7970 (PCI-E 3.0)	133.080
Radeon HD 7970 (PCI-E 2.0)	132.470	0%
GeForce GTX 580	131.477	1%
Radeon HD 6970	121.214	10%

Battlefield 3

Battlefield 3 is the latest installment in the Battlefield franchise released in 2011. It is based on the Frostbite 2 engine, which is DirectX 11. In order to measure performance using this game, we walked our way through the first half of the “Operation Swordbreaker” mission, measuring the number of frames per second using FRAPS. We ran this game at 1920x1200 and 2560x1600, maximizing all image quality settings, configuring anti-aliasing as “4xMSAA” and anisotropic filtering at “16x.”

Battlefield 3	1920x1200	Difference
Radeon HD 7970 (PCI-E 3.0)	56.743
Radeon HD 7970 (PCI-E 2.0)	56.181	1%
Radeon HD 6970	50.773	12%
GeForce GTX 580	50.369	13%

Battlefield 3	2560x1600	Difference
Radeon HD 7970 (PCI-E 2.0)	42.987	2%
Radeon HD 7970 (PCI-E 3.0)	42.312
GeForce GTX 580	38.914	9%
Radeon HD 6970	37.448	13%

3DMark 11 Professional

3DMark 11 Professional measures Shader 5.0 (i.e., DirectX 11) performance. We ran this program at 1920x1200 and 2560x1600, selecting the four graphics tests available and deselecting the other tests available. We used two image quality settings, “performance” and “extreme,” both at their default settings. The results being compared are the “GPU Score” achieved by each video card.

3DMark 11 - Performance	1920x1200	Difference
Radeon HD 7970 (PCI-E 3.0)	4026
Radeon HD 7970 (PCI-E 2.0)	3968	1%
Radeon HD 6970	3724	8%
GeForce GTX 580	3152	28%

3DMark 11 - Performance	2560x1600	Difference
Radeon HD 7970 (PCI-E 2.0)	2383	1%
Radeon HD 7970 (PCI-E 3.0)	2353
Radeon HD 6970	2175	8%
GeForce GTX 580	1846	27%

3DMark 11 - Extreme	1920x1200	Difference
Radeon HD 7970 (PCI-E 3.0)	2476
Radeon HD 7970 (PCI-E 2.0)	2439	2%
Radeon HD 6970	2144	15%
GeForce GTX 580	1892	31%

3DMark 11 - Extreme	2560x1600	Difference
Radeon HD 7970 (PCI-E 3.0)	1537
Radeon HD 7970 (PCI-E 2.0)	1519	1%
Radeon HD 6970	1302	18%
GeForce GTX 580	1153	33%

Media Espresso 6.5

Media Espresso is a video conversion program that uses the graphics processing unit of the video card to speed up the conversion process. We converted a 449 MB, 1920x1080i, 18,884 kbps, MPEG2 video file to a smaller 640x360, H.264, .MPG4 file for viewing on a portable device such as an iPhone or iPod Touch. We also ran this test on our two CPUs (Core i7-980X and Core i7-3960X) in order to compare the difference in performance of using a high-end CPU and a high-end GPU to transcode video.

Media Espresso 6.5	Seconds	Difference
Radeon HD 7970 (PCI-E 3.0)	29
Radeon HD 7970 (PCI-E 2.0)	36	19%
GeForce GTX 580	44	34%
Core i7-3960X	46	37%
Radeon HD 6970	48	40%
Core i7-980X	65	55%

Conclusions

The Radeon HD 7970 proved to be the fastest single-GPU video card ever released. It was between 8% and 33% faster than the GeForce GTX 580 in most games we ran. The exceptions were Deus Ex: Human Revolution, where both video cards achieved the same performance level, and Far Cry 2, where the NVIDIA video card was 13% faster at 1920x1200, with both achieving the same performance level at 2560x1600.

Using the video card for video encoding with Media Espresso 6.5, we saw the Radeon HD 7970 running 52% faster than the GeForce GTX 580, 59% faster than a Core i7-3960X CPU (which is the fastest desktop CPU available on the market today), and 124% faster than a Core i7-980X, making it a terrific video card for accelerating processing using the GPGPU technique.

In this review, we could answer one of the most common questions about this new video card: Will I lose performance if I install it on a PCI Express 2.0 system? The answer is no. In our test, we saw no performance difference between running this video card on a PCI Express 3.0 system and running it on a PCI Express 2.0 system, as current games are not saturating the bandwidth provided by the PCI Express 2.0 connection. This is really good news for users who don’t want to sell a kidney to buy a new system based on a “Sandy Bridge-E” processor. However, we saw a significant 24% performance difference between PCI Express 3.0 and 2.0 when running Media Espresso. This means that for using the video card to process general computing tasks, it is better to have the PCI Express 3.0 platform.

The only problem with this video card is, of course, its price. It is better than the GeForce GTX 580, but that doesn’t mean that the average user can afford it. If money isn’t an issue, buy the new Radeon HD 7970 and be happy!