Radeon HD 4870 512MB vs Radeon HD 6770

Intro

Compare all that to the Radeon HD 6770, which has a GPU core clock speed of 900 MHz, and 512 MB of GDDR5 RAM set to run at 1050 MHz through a 128-bit bus. It also is made up of 800 Stream Processors, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6770		108 Watts
Radeon HD 4870 512MB		150 Watts
	Difference: 42 Watts (39%)

Memory Bandwidth

The Radeon HD 4870 512MB should in theory perform a lot faster than the Radeon HD 6770 in general. (explain)

Radeon HD 4870 512MB		115200 MB/sec
Radeon HD 6770		67200 MB/sec
	Difference: 48000 (71%)

Texel Rate

The Radeon HD 6770 will be a bit (more or less 20%) faster with regards to AF than the Radeon HD 4870 512MB. (explain)

Radeon HD 6770		36000 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 6000 (20%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 6770 is the winner, not by a very large margin though. (explain)

Radeon HD 6770		14400 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 2400 (20%)

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 largest amount of information (counted in MB per second) that can be moved over the external memory interface in one second. The number is calculated by multiplying the card's interface width by its memory clock speed. If the card has DDR type RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.