Radeon HD 4870 X2 vs Radeon HD 6870

Intro

Compare that to the Radeon HD 6870, which has GPU core speed of 900 MHz, and 1024 MB of GDDR5 RAM set to run at 1050 MHz through a 256-bit bus. It also is comprised of 1120 Stream Processors, 56 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6870		151 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 199 Watts (132%)

Memory Bandwidth

As far as performance goes, the Radeon HD 4870 X2 should in theory be a lot superior to the Radeon HD 6870 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon HD 6870		134400 MB/sec
	Difference: 96000 (71%)

Texel Rate

The Radeon HD 4870 X2 will be a little bit (more or less 19%) better at anisotropic filtering than the Radeon HD 6870. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon HD 6870		50400 Mtexels/sec
	Difference: 9600 (19%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6870 is a better choice, but it probably won't make a huge difference. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 4800 (20%)

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: Memory bandwidth is the largest amount of data (counted in megabytes per second) that can be transferred past the external memory interface in a second. The number is calculated by multiplying the bus width by the speed of its memory. In the case of DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The better 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 maximum amount of pixels the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.