Radeon HD 3870 X2 512MB vs Radeon HD 4770

Intro

Compare those specifications to the Radeon HD 4770, which has core clock speeds of 750 MHz on the GPU, and 800 MHz on the 512 MB of GDDR5 memory. It features 640(128x5) SPUs along with 32 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 3870 X2 512MB should theoretically be a lot better than the Radeon HD 4770 overall. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 64000 (125%)

Texel Rate

The Radeon HD 3870 X2 512MB is a bit (more or less 10%) better at texture filtering than the Radeon HD 4770. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 2400 (10%)

Pixel Rate

The Radeon HD 3870 X2 512MB should be a lot (more or less 120%) better at full screen anti-aliasing than the Radeon HD 4770, and will be able to handle higher screen resolutions without slowing down too much. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 4770		12000 Mpixels/sec
	Difference: 14400 (120%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of information (in units of megabytes per second) that can be transported past the external memory interface within a second. It is calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR type memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster 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 applied per second. This figure is calculated by multiplying the total number of texture units by the core speed of the chip. The higher the texel rate, the better the graphics 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 maximum number of pixels that the graphics chip could possibly record to its local memory in a second - measured in millions of pixels per second. The number 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 filling the screen with pixels (the image). The actual pixel rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.