Radeon HD 4890 2GB vs Radeon HD 6870

Intro

Compare those specs to the Radeon HD 6870, which has core clock speeds of 900 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 memory. It features 1120 SPUs as well as 56 TAUs and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6870		151 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 39 Watts (26%)

Memory Bandwidth

The Radeon HD 6870 should theoretically be just a bit faster than the Radeon HD 4890 2GB in general. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 9600 (8%)

Texel Rate

The Radeon HD 6870 should be quite a bit (about 26%) more effective at AF than the Radeon HD 4890 2GB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 10400 (26%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 6870 is a better choice, by far. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 12800 (80%)

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 (measured in MB per second) that can be moved past the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. In the case of DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher this number, the better the card will be at handling 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 a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour 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 output rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.