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AMD Radeon HD 6990 - The New King of Graphics

By Kenny Yeo - 19 Mar 2011

The Dual-GPU Monster

The Dual-GPU Monster

Since the Radeon HD 3000 series, AMD’s (previously ATI) flagship cards have been dual-GPU monsters. This trend began in early 2008 with the Radeon HD 3870 X2 and was succeeded by the Radeon HD 4870 X2 and then the Radeon HD 5970. And with the introduction of their newest Radeon HD 6000 series (Northern Islands), graphics enthusiasts and power-hungry gamers are eagerly waiting AMD’s next dual-GPU creation.

And it is finally here. The new AMD flagship is the Radeon HD 6990, and it is easily the most powerful card AMD has ever built. Additionally, AMD also claims that it is the most powerful single graphics card in the world. Unfortunately, the AMD Radeon HD 6990 is off to a bad start because first and foremost, like the old Radeon HD 5970, which is really powered by two “detuned” Cypress XT (Radeon HD 5870) chips; the new Radeon HD 6990 is somewhat the same.

To be specific, while the Radeon HD 6990 has two Cayman XT chips with the full 1536 stream processing units, giving it a grand total of 3072 stream processing units, through the use of the dual BIOS functionality of the Radeon HD 6970 and HD 6950, the Radeon HD 6990 has a default mode and OC mode. In default mode, the card runs at 830MHz at the core and 5000MHz DDR at the memory. These clock speeds are substantially lower than a Radeon HD 6970. Furthermore, in this mode, the BIOS is write-protected and therefore the card cannot be overclocked. Put in OC mode, however, and the Radeon HD 6990 will run at higher clock speeds, 880MHz at the core (similar to the Radeon HD 6970) but retains memory speeds of 5000MHz DDR.

AMD's latest flagship is here to reclaim the title of world's fastest single graphics card from NVIDIA. We've with us an ASUS Radeon HD 6990 for evaluation, which is as good as any other offered by the competition since all of them adhere to the reference design and requirements.

Clock speeds aside, the Radeon HD 6990 is in every other sense, double the card of the Radeon HD 6970. Not only does it have double the number of stream processing units, it also has twice the number of texture mapping units and raster operating units, as well as  double the framebuffer - a whopping 4GB.

All things considered and even with the slightly stunted clock speeds, the Radeon HD 6990 is a beast of a card and we can’t wait to put it through our benchmarks to find out how fast it will run. Naturally, we are expecting to see some eye-popping numbers. But before we proceed, here’s a look at how the Radeon HD 6990 measures up against its closest rivals. 


AMD Radeon HD 6900 series and competitive SKUs compared
Model AMD Radeon HD 6990 AMD Radeon HD 6970 AMD Radeon HD 6950 ATI Radeon
HD 5970
GTX 580
GTX 570
Core Code Antilles Cayman XT Cayman PRO Hemlock GF110 GF110
Transistor Count 5280 million  2640 million 2640 million 4300 million 3000 million 3000 million
40nm 40nm 40nm 40nm 40nm 40nm
Core Clock 830 / 880MHz 880MHz 800MHz 725MHz 772MHz 732MHz
Stream Processors 3072 Stream Processing units 1536 Stream processing units 1408 Stream Processing units 3200 Stream processing units 512 Steam Processors 480 Stream Processors
Stream Processor Clock 830 / 880MHz 880MHz 800MHz 725MHz 1544MHz 1464MHz
Texture Mapping
Units (TMU) /
Texture Filtering
(TF) units
192 96 88 160 64 60
Raster Operator
units (ROP)
64 32 32 64 48 40
Memory Clock 5000MHz GDDR5 5500MHz GDDR5 5000MHz GDDR5 4000MHz GDDR5 4008MHz GDDR5 3800MHz GDDR5
DDR Memory Bus 512-bit
256-bit 256-bit 256-bit 384-bit 320-bit
320GB/s  176.0GB/s 160.0GB/s 256GB/s 192.4GB/s 152GB/s
PCI Express
PCIe ver 2.0 x16 PCIe ver 2.0 x16 PCIe ver 2.0 x16 PCIe ver 2.0 x16 PCIe ver 2.0 x16 PCIe ver 2.0 x16
Molex Power
2 x 8-pin 1 x 6-pin, 1 x 8-pin 2 x 6-pin 1 x 6-pin, 1 x 8-pin 1 x 6-pin, 1 x 8-pin 2 x 6-pin
Multi GPU
CrossFireX CrossFireX CrossFireX CrossFireX SLI SLI
DVI Output Support 1 x Dual-link 1 x Dual-Link, 1 x Single-Link 1 x Dual-Link, 1 x Single-Link 2 x Dual-Link 2 x Dual-Link 2 x Dual-Link
HDMI None 1 1 1 1 (mini-HDMI) 1 (mini-HDMI)
DisplayPort 4
(mini DisplayPort 1.2)
(version 1.2)
(version 1.2)
1 None None
HDCP Output
Yes Yes Yes Yes Yes Yes
Street Price Launch price: US$700 ~US$369  ~US$279 ~US$500 ~US$529 ~US$359


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