Radeon HD 4870 512MB vs Radeon HD 6850

Intro

Compare all of that to the Radeon HD 6850, which uses a 40 nm design. AMD has clocked the core frequency at 775 MHz. The GDDR5 RAM is set to run at a frequency of 1000 MHz on this particular model. It features 960 SPUs as well as 48 Texture Address Units and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6850		127 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 23 Watts (18%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6850 will be 11% quicker than the Radeon HD 4870 512MB overall, because of its higher bandwidth. (explain)

Radeon HD 6850		128000 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 12800 (11%)

Texel Rate

The Radeon HD 6850 should be quite a bit (about 24%) faster with regards to AF than the Radeon HD 4870 512MB. (explain)

Radeon HD 6850		37200 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 7200 (24%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6850 is superior to the Radeon HD 4870 512MB, and very much so. (explain)

Radeon HD 6850		24800 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 12800 (107%)

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 largest amount of information (counted in MB per second) that can be moved past the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory speed. In the case of DDR RAM, it must be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly write to the local memory in a 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 speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.