Radeon HD 4870 2GB vs Radeon HD 6870

Intro

Compare those specifications to the Radeon HD 6870, which makes use of a 40 nm design. AMD has set the core frequency at 900 MHz. The GDDR5 RAM works 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

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 2GB		150 Watts
Radeon HD 6870		151 Watts
	Difference: 1 Watts (1%)

Memory Bandwidth

In theory, the Radeon HD 6870 should perform a bit faster than the Radeon HD 4870 2GB in general. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4870 2GB		115200 MB/sec
	Difference: 19200 (17%)

Texel Rate

The Radeon HD 6870 is a lot (approximately 68%) faster with regards to anisotropic filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 20400 (68%)

Pixel Rate

The Radeon HD 6870 will be quite a bit (approximately 140%) faster with regards to full screen anti-aliasing than the Radeon HD 4870 2GB, and also capable of handling higher resolutions more effectively. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 16800 (140%)

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 (in units of megabytes per second) that can be moved over the external memory interface within a second. The number is calculated by multiplying the card's bus width by its memory speed. If it uses DDR memory, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The higher this number, 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 maximum number of pixels that the graphics chip could possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.