Radeon HD 4870 X2 vs Radeon HD 6970

Intro

Compare all of that to the Radeon HD 6970, which comes with GPU clock speed of 880 MHz, and 2048 MB of GDDR5 memory running at 1375 MHz through a 256-bit bus. It also features 1536 Stream Processors, 96 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6970		250 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 100 Watts (40%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 should be 31% faster than the Radeon HD 6970 in general, due to its higher data rate. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6970		176000 MB/sec
	Difference: 54400 (31%)

Texel Rate

The Radeon HD 6970 should be a lot (more or less 41%) faster with regards to texture filtering than the Radeon HD 4870 X2. (explain)

Radeon HD 6970		84480 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 24480 (41%)

Pixel Rate

The Radeon HD 6970 should be just a bit (approximately 17%) more effective at full screen anti-aliasing than the Radeon HD 4870 X2, and also will be able to handle higher resolutions while still performing well. (explain)

Radeon HD 6970		28160 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 4160 (17%)

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

Specifications

Memory Bandwidth: Bandwidth is the maximum amount of data (counted in megabytes per second) that can be transferred across the external memory interface in a second. The number is worked out by multiplying the card's bus width by its memory clock speed. If the card has DDR memory, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. 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 potential to reach the max fill rate.