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Radeon HD 3870 X2 1GB vs Radeon HD 6990

Intro

The Radeon HD 3870 X2 1GB uses a 55 nm design. AMD has clocked the core frequency at 825 MHz. The GDDR4 RAM works at a speed of 1126 MHz on this model. It features 320(64x5) SPUs as well as 16 TAUs and 16 Rasterization Operator Units.

Compare all of that to the Radeon HD 6990, which uses a 40 nm design. AMD has clocked the core speed at 830 MHz. The GDDR5 memory is set to run at a speed of 1250 MHz on this card. It features 1536 SPUs along with 96 Texture Address Units and 32 Rasterization Operator Units.

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 6990 should theoretically be a lot superior to the Radeon HD 3870 X2 1GB in general. (explain)

Radeon HD 6990 320000 MB/sec
Radeon HD 3870 X2 1GB 144128 MB/sec
Difference: 175872 (122%)

Texel Rate

The Radeon HD 6990 should be much (approximately 504%) more effective at anisotropic filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 6990 159360 Mtexels/sec
Radeon HD 3870 X2 1GB 26400 Mtexels/sec
Difference: 132960 (504%)

Pixel Rate

The Radeon HD 6990 will be much (approximately 101%) better at anti-aliasing than the Radeon HD 3870 X2 1GB, and will be capable of handling higher resolutions better. (explain)

Radeon HD 6990 53120 Mpixels/sec
Radeon HD 3870 X2 1GB 26400 Mpixels/sec
Difference: 26720 (101%)

Please note that the above 'benchmarks' are all just theoretical - the results were calculated based on the card's specifications, and real-world performance may (and probably will) vary at least a bit.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

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Radeon HD 3870 X2 1GB

Amazon.com

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Radeon HD 6990

Amazon.com

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Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.

Specifications

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Model Radeon HD 3870 X2 1GB Radeon HD 6990
Manufacturer AMD AMD
Year Jan 28, 2008 March 2011
Code Name R680 Antilles
Memory 1024 MB (x2) 2048 MB (x2)
Core Speed 825 MHz (x2) 830 MHz (x2)
Memory Speed 2252 MHz (x2) 5000 MHz (x2)
Power (Max TDP) (Unknown) watts 375 watts
Bandwidth 144128 MB/sec 320000 MB/sec
Texel Rate 26400 Mtexels/sec 159360 Mtexels/sec
Pixel Rate 26400 Mpixels/sec 53120 Mpixels/sec
Unified Shaders 320(64x5) (x2) 1536 (x2)
Texture Mapping Units 16 (x2) 96 (x2)
Render Output Units 16 (x2) 32 (x2)
Bus Type GDDR4 GDDR5
Bus Width 256-bit (x2) 256-bit (x2)
Fab Process 55 nm 40 nm
Transistors (Unknown) million 2640 million
Bus PCIe 2.0 x16/(internal PCIe 1.1 x16) PCIe 2.1 x16
DirectX Version DirectX 10.1 DirectX 11
OpenGL Version OpenGL 3.0 OpenGL 4.1

Memory Bandwidth: Memory bandwidth is the max amount of information (measured in megabytes per second) that can be moved over the external memory interface within a second. It is worked out by multiplying the interface width by the speed of its memory. If the card has DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This figure is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.

Display Prices

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Radeon HD 3870 X2 1GB

Amazon.com

Check prices at:

Radeon HD 6990

Amazon.com

Check prices at:

Please note that the price comparisons are based on search keywords - sometimes it might show cards with very similar names that are not exactly the same as the one chosen in the comparison. We do try to filter out the wrong results as best we can, though.

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