Radeon HD 4870 2GB vs Radeon HD 6950

Intro

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

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

In theory, the Radeon HD 6950 will be 39% faster than the Radeon HD 4870 2GB overall, because of its higher bandwidth. (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 a lot (about 135%) better at texture filtering 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 (approximately 113%) better at AA 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 max amount of information (in units of megabytes per second) that can be transferred across the external memory interface in a second. It is calculated by multiplying the card's bus width by its memory speed. If the card has DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, 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 amount of texture map elements (texels) that can be processed in one second. This figure is calculated 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 handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.