Radeon HD 4890 1GB vs Radeon HD 6950 2GB

Intro

Compare that to the Radeon HD 6950 2GB, which comes with a GPU core clock speed of 800 MHz, and 2048 MB of GDDR5 RAM running at 1250 MHz through a 256-bit bus. It also is made up of 1408 Stream Processors, 88 TAUs, and 32 ROPs.

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

Performance-wise, the Radeon HD 6950 2GB should in theory be quite a bit better than the Radeon HD 4890 1GB overall. (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 will be quite a bit (more or less 76%) more effective at anisotropic 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

The Radeon HD 6950 2GB should be a lot (approximately 60%) better at anti-aliasing than the Radeon HD 4890 1GB, and also should be able to handle higher screen resolutions while still performing well. (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 maximum amount of information (counted in megabytes per second) that can be transferred across the external memory interface in a second. It is worked out by multiplying the bus width by the speed of its memory. In the case of DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The better this number, the better the 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 number of pixels the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount 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 is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.