Radeon HD 4890 2GB vs Radeon HD 6950 2GB

Intro

Compare those specs to the Radeon HD 6950 2GB, which features core clock speeds of 800 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 memory. It features 1408 SPUs as well as 88 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4890 2GB		190 Watts
Radeon HD 6950 2GB		200 Watts
	Difference: 10 Watts (5%)

Memory Bandwidth

The Radeon HD 6950 2GB, in theory, should perform quite a bit faster than the Radeon HD 4890 2GB in general. (explain)

Radeon HD 6950 2GB		160000 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 35200 (28%)

Texel Rate

The Radeon HD 6950 2GB should be a lot (approximately 76%) faster with regards to texture filtering than the Radeon HD 4890 2GB. (explain)

Radeon HD 6950 2GB		70400 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 30400 (76%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 6950 2GB is the winner, and very much so. (explain)

Radeon HD 6950 2GB		25600 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 9600 (60%)

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: Bandwidth is the largest amount of data (measured in megabytes per second) that can be transferred across the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory speed. If the card has DDR type memory, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the video 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 the video card can possibly record to the local memory in one 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 - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.