Radeon HD 4870 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 frequency of 1050 MHz on this specific model. It features 1120 SPUs along with 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

As far as performance goes, the Radeon HD 6870 should theoretically be a bit superior to the Radeon HD 4870 2GB overall. (explain)

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

Texel Rate

The Radeon HD 6870 should be 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 is much (about 140%) better at FSAA than the Radeon HD 4870 2GB, and also should be able to handle higher resolutions without losing too much performance. (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: Bandwidth is the max amount of data (in units of MB per second) that can be transported across the external memory interface within a second. It's calculated by multiplying the bus width by its memory clock speed. If the card has DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This is calculated by multiplying the total amount of texture units of the card 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 processed in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs 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 rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.