Radeon HD 3870 X2 1GB vs Radeon HD 7870

Intro

Compare all of that to the Radeon HD 7870, which comes with GPU core speed of 1000 MHz, and 2048 MB of GDDR5 RAM set to run at 1200 MHz through a 256-bit bus. It also is comprised of 1280 Stream Processors, 80 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon HD 7870 should in theory be a little bit faster than the Radeon HD 3870 X2 1GB in general. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 3870 X2 1GB		144128 MB/sec
	Difference: 9472 (7%)

Texel Rate

The Radeon HD 7870 is a lot (approximately 203%) more effective at AF than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 53600 (203%)

Pixel Rate

The Radeon HD 7870 is a lot (about 21%) more effective at anti-aliasing than the Radeon HD 3870 X2 1GB, and should be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 3870 X2 1GB		26400 Mpixels/sec
	Difference: 5600 (21%)

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 largest amount of information (in units of MB per second) that can be moved across the external memory interface in one second. The number is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.