Radeon HD 4890 2GB vs Radeon HD 6870

Intro

Compare those specs to the Radeon HD 6870, which uses a 40 nm design. AMD has set the core speed at 900 MHz. The GDDR5 RAM is set to run at a speed of 1050 MHz on this model. It features 1120 SPUs as well as 56 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

Hide Graphs

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

Theoretically speaking, the Radeon HD 6870 should be just a bit faster than the Radeon HD 4890 2GB overall. (explain)

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

Texel Rate

The Radeon HD 6870 is quite a bit (approximately 26%) more effective at texture filtering 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 superior to the Radeon HD 4890 2GB, by a large margin. (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 maximum amount of information (in units of MB per second) that can be transferred across the external memory interface within a second. It is worked out by multiplying the interface width by the speed of its memory. If it uses DDR RAM, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better 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 can be applied in one second. This figure is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the most pixels the video card could possibly write to the local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.