Radeon HD 4870 2GB vs Radeon HD 6950

Intro

Compare those specs to the Radeon HD 6950, which features clock speeds of 800 MHz on the GPU, and 1250 MHz on the 1024 MB of GDDR5 memory. It features 1408 SPUs as well as 88 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 2GB		150 Watts
Radeon HD 6950		200 Watts
	Difference: 50 Watts (33%)

Memory Bandwidth

The Radeon HD 6950, in theory, should perform much faster than the Radeon HD 4870 2GB overall. (explain)

Radeon HD 6950		160000 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 44800 (39%)

Texel Rate

The Radeon HD 6950 will be quite a bit (approximately 135%) better at AF than the Radeon HD 4870 2GB. (explain)

Radeon HD 6950		70400 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 40400 (135%)

Pixel Rate

The Radeon HD 6950 will be quite a bit (more or less 113%) better at FSAA than the Radeon HD 4870 2GB, and should be able to handle higher resolutions more effectively. (explain)

Radeon HD 6950		25600 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 13600 (113%)

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.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the largest amount of information (counted in megabytes per second) that can be transferred past the external memory interface within a second. It's worked out by multiplying the interface width by the speed of its memory. In the case of DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster 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 are processed per second. This number is calculated by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the the card's clock speed. 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 also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.