Radeon HD 4870 X2 vs Radeon R9 285

Intro

Compare all that to the Radeon R9 285, which has a GPU core clock speed of 918 MHz, and 2048 MB of GDDR5 memory set to run at 1375 MHz through a 256-bit bus. It also is comprised of 1792 Stream Processors, 112 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 285		190 Watts
Radeon HD 4870 X2		350 Watts
	Difference: 160 Watts (84%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4870 X2 should be much faster than the Radeon R9 285 in general. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon R9 285		176000 MB/sec
	Difference: 54400 (31%)

Texel Rate

The Radeon R9 285 should be a lot (more or less 71%) more effective at AF than the Radeon HD 4870 X2. (explain)

Radeon R9 285		102816 Mtexels/sec
Radeon HD 4870 X2		60000 Mtexels/sec
	Difference: 42816 (71%)

Pixel Rate

The Radeon R9 285 will be quite a bit (more or less 22%) better at anti-aliasing than the Radeon HD 4870 X2, and should be able to handle higher resolutions without losing too much performance. (explain)

Radeon R9 285		29376 Mpixels/sec
Radeon HD 4870 X2		24000 Mpixels/sec
	Difference: 5376 (22%)

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 data (counted in MB per second) that can be moved across the external memory interface in one second. It's worked out by multiplying the card's bus width by the speed of its memory. If it uses DDR type RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.