Radeon HD 4850 512MB vs Radeon HD 6870

Intro

Compare those specs to the Radeon HD 6870, which features a clock speed of 900 MHz and a GDDR5 memory frequency of 1050 MHz. It also features a 256-bit bus, and uses a 40 nm design. It is made up 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 512MB		110 Watts
Radeon HD 6870		151 Watts
	Difference: 41 Watts (37%)

Memory Bandwidth

Performance-wise, the Radeon HD 6870 should in theory be quite a bit superior to the Radeon HD 4850 512MB overall. (explain)

Radeon HD 6870		134400 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 70848 (111%)

Texel Rate

The Radeon HD 6870 will be a lot (about 102%) more effective at AF than the Radeon HD 4850 512MB. (explain)

Radeon HD 6870		50400 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 25400 (102%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon HD 6870 is a better choice, and very much so. (explain)

Radeon HD 6870		28800 Mpixels/sec
Radeon HD 4850 512MB		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 data (measured in MB per second) that can be transferred over the external memory interface in one second. The number is calculated by multiplying the card's bus width by the speed of its memory. If the card has DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the 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 amount of texture map elements (texels) that are applied per second. This is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The better the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.