Radeon HD 4850 2GB vs Radeon HD 6870

Intro

Compare those specs to the Radeon HD 6870, which has a clock frequency of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also makes use of a 256-bit bus, and uses a 40 nm design. It is comprised of 1120 SPUs, 56 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4850 2GB		110 Watts
Radeon HD 6870		151 Watts
	Difference: 41 Watts (37%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6870 should perform quite a bit faster than the Radeon HD 4850 2GB in general. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 70848 (111%)

Texel Rate

The Radeon HD 6870 will be much (about 102%) more effective at anisotropic filtering than the Radeon HD 4850 2GB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 25400 (102%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6870 is superior to the Radeon HD 4850 2GB, by a large margin. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4850 2GB		10000 Mpixels/sec
	Difference: 18800 (188%)

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 megabytes 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 speed. In the case of DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.