Radeon HD 4890 1GB vs Radeon HD 6950

Intro

Compare all that to the Radeon HD 6950, which features a clock frequency of 800 MHz and a GDDR5 memory speed of 1250 MHz. It also features a 256-bit memory bus, and uses a 40 nm design. It is made up of 1408 SPUs, 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		200 Watts
	Difference: 10 Watts (5%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6950 is 28% quicker than the Radeon HD 4890 1GB overall, because of its higher bandwidth. (explain)

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

Texel Rate

The Radeon HD 6950 should be quite a bit (about 76%) faster with regards to anisotropic filtering than the Radeon HD 4890 1GB. (explain)

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

Pixel Rate

The Radeon HD 6950 should be much (approximately 60%) more effective at full screen anti-aliasing than the Radeon HD 4890 1GB, and also should be capable of handling higher resolutions better. (explain)

Radeon HD 6950		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 largest amount of information (measured in MB per second) that can be transferred past the external memory interface in a second. The number is calculated by multiplying the interface width by the speed of its memory. If it uses DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This number is worked out by multiplying the total number of texture units by the core 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka 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 get to the maximum fill rate.