Radeon HD 4870 512MB vs Radeon HD 6870

Intro

Compare those specifications to the Radeon HD 6870, which features core clock speeds of 900 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 RAM. It features 1120 SPUs along with 56 Texture Address Units and 32 ROPs.

(No game benchmarks for this combination yet.)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4870 512MB		150 Watts
Radeon HD 6870		151 Watts
	Difference: 1 Watts (1%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6870 should be just a bit faster than the Radeon HD 4870 512MB overall. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 19200 (17%)

Texel Rate

The Radeon HD 6870 is a lot (about 68%) better at texture filtering than the Radeon HD 4870 512MB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 20400 (68%)

Pixel Rate

The Radeon HD 6870 is quite a bit (approximately 140%) more effective at full screen anti-aliasing than the Radeon HD 4870 512MB, and will be capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4870 512MB		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 information (counted in MB per second) that can be transferred across the external memory interface in one second. It is calculated by multiplying the card's bus width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher 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 number of texture map elements (texels) that are processed in one second. This figure is calculated by multiplying the total amount of texture units by the core speed of the chip. The better the texel rate, 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 record to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.