Radeon HD 3870 X2 1GB vs Radeon RX 580

Intro

Compare those specifications to the Radeon RX 580, which features clock speeds of 1257 MHz on the GPU, and 2000 MHz on the 8192 MB of GDDR5 memory. It features 2304 SPUs as well as 144 TAUs and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

The Radeon RX 580 should theoretically be much faster than the Radeon HD 3870 X2 1GB overall. (explain)

Radeon RX 580		262144 MB/sec
Radeon HD 3870 X2 1GB		144128 MB/sec
	Difference: 118016 (82%)

Texel Rate

The Radeon RX 580 is much (more or less 586%) more effective at texture filtering than the Radeon HD 3870 X2 1GB. (explain)

Radeon RX 580		181008 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 154608 (586%)

Pixel Rate

The Radeon RX 580 is quite a bit (about 52%) better at anti-aliasing than the Radeon HD 3870 X2 1GB, and will be capable of handling higher screen resolutions more effectively. (explain)

Radeon RX 580		40224 Mpixels/sec
Radeon HD 3870 X2 1GB		26400 Mpixels/sec
	Difference: 13824 (52%)

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: Bandwidth is the maximum amount of information (measured in megabytes per second) that can be transferred across the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs 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 output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.