Radeon HD 4890 2GB vs Radeon HD 6950 2GB

Intro

Compare that to the Radeon HD 6950 2GB, which has a clock frequency of 800 MHz and a GDDR5 memory speed of 1250 MHz. It also uses a 256-bit memory bus, and uses a 40 nm design. It is made up of 1408 SPUs, 88 Texture Address Units, 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 should theoretically perform much 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 will be a lot (about 76%) faster with regards to AF 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

The Radeon HD 6950 2GB should be quite a bit (approximately 60%) faster with regards to anti-aliasing than the Radeon HD 4890 2GB, and able to handle higher screen resolutions more effectively. (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: Memory bandwidth is the max amount of information (measured in MB per second) that can be transported across the external memory interface in a second. It is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This is calculated by multiplying the total amount of texture units by the core speed of the chip. The higher this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.