Radeon HD 3870 X2 1GB vs Radeon HD 5870

Intro

Compare those specifications to the Radeon HD 5870, which comes with core clock speeds of 850 MHz on the GPU, and 1200 MHz on the 1024 MB of GDDR5 memory. It features 1600(320x5) SPUs along with 80 Texture Address Units and 32 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 5870 will be 7% quicker than the Radeon HD 3870 X2 1GB in general, due to its higher data rate. (explain)

Radeon HD 5870		153600 MB/sec
Radeon HD 3870 X2 1GB		144128 MB/sec
	Difference: 9472 (7%)

Texel Rate

The Radeon HD 5870 is a lot (about 158%) better at AF than the Radeon HD 3870 X2 1GB. (explain)

Radeon HD 5870		68000 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 41600 (158%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 5870 is superior to the Radeon HD 3870 X2 1GB, though not by far. (explain)

Radeon HD 5870		27200 Mpixels/sec
Radeon HD 3870 X2 1GB		26400 Mpixels/sec
	Difference: 800 (3%)

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 data (in units of megabytes per second) that can be transported over the external memory interface within a second. It is worked out by multiplying the bus width by the speed of its memory. In the case of DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better 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 amount of texture map elements (texels) that are applied per second. This number is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, the better the 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 most pixels the graphics card can possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.