Radeon HD 4890 2GB vs Radeon HD 7870

Intro

Compare all of that to the Radeon HD 7870, which has a core clock speed of 1000 MHz and a GDDR5 memory speed of 1200 MHz. It also uses a 256-bit bus, and uses a 28 nm design. It is made up of 1280 SPUs, 80 Texture Address Units, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870		175 Watts
Radeon HD 4890 2GB		190 Watts
	Difference: 15 Watts (9%)

Memory Bandwidth

The Radeon HD 7870 should in theory be quite a bit faster than the Radeon HD 4890 2GB overall. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4890 2GB		124800 MB/sec
	Difference: 28800 (23%)

Texel Rate

The Radeon HD 7870 should be much (approximately 100%) better at AF than the Radeon HD 4890 2GB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4890 2GB		40000 Mtexels/sec
	Difference: 40000 (100%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 7870 is the winner, by a large margin. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4890 2GB		16000 Mpixels/sec
	Difference: 16000 (100%)

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: Bandwidth is the maximum amount of data (measured in MB per second) that can be transferred past the external memory interface within a second. It's worked out by multiplying the bus width by the speed of its memory. If it uses 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 anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.