Radeon HD 3870 X2 512MB vs Radeon HD 7770

Intro

Compare that to the Radeon HD 7770, which makes use of a 28 nm design. AMD has set the core frequency at 1000 MHz. The GDDR5 memory works at a speed of 1125 MHz on this card. It features 640 SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 3870 X2 512MB should theoretically be much faster than the Radeon HD 7770 overall. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 43200 (60%)

Texel Rate

The Radeon HD 7770 should be quite a bit (approximately 52%) better at AF than the Radeon HD 3870 X2 512MB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 13600 (52%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 3870 X2 512MB is the winner, by a large margin. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon HD 7770		16000 Mpixels/sec
	Difference: 10400 (65%)

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 maximum amount of information (counted in MB per second) that can be transferred over the external memory interface in a second. It is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR RAM, it should be multiplied by 2 again. If it uses 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 texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total amount of texture units by the core clock 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 a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.