Radeon HD 4890 1GB vs Radeon HD 6950 2GB

Intro

Compare all that to the Radeon HD 6950 2GB, which comes with clock speeds of 800 MHz on the GPU, and 1250 MHz on the 2048 MB of GDDR5 memory. It features 1408 SPUs along with 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 4890 1GB		190 Watts
Radeon HD 6950 2GB		200 Watts
	Difference: 10 Watts (5%)

Memory Bandwidth

In theory, the Radeon HD 6950 2GB is 28% faster than the Radeon HD 4890 1GB in general, due to its greater data rate. (explain)

Radeon HD 6950 2GB		160000 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 35200 (28%)

Texel Rate

The Radeon HD 6950 2GB should be a lot (about 76%) better at texture filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 6950 2GB		70400 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 30400 (76%)

Pixel Rate

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

Radeon HD 6950 2GB		25600 Mpixels/sec
Radeon HD 4890 1GB		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: Memory bandwidth is the max amount of data (counted in 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 the speed of its memory. If the card has DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the better 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 texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels 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 amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.