Radeon HD 3870 X2 512MB vs Radeon R9 M390X

Intro

Compare that to the Radeon R9 M390X, which has a GPU core clock speed of 723 MHz, and 4096 MB of GDDR5 RAM set to run at 1250 MHz through a 256-bit bus. It also features 2048 SPUs, 128 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon R9 M390X is 39% quicker than the Radeon HD 3870 X2 512MB in general, due to its higher data rate. (explain)

Radeon R9 M390X		160000 MB/sec
Radeon HD 3870 X2 512MB		115200 MB/sec
	Difference: 44800 (39%)

Texel Rate

The Radeon R9 M390X is much (approximately 251%) faster with regards to anisotropic filtering than the Radeon HD 3870 X2 512MB. (explain)

Radeon R9 M390X		92544 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 66144 (251%)

Pixel Rate

The Radeon HD 3870 X2 512MB should be a little bit (about 14%) faster with regards to AA than the Radeon R9 M390X, and also will be capable of handling higher screen resolutions without slowing down too much. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon R9 M390X		23136 Mpixels/sec
	Difference: 3264 (14%)

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 megabytes per second) that can be transferred over the external memory interface within a second. It's calculated by multiplying the bus width by its memory clock speed. If the card has DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This number is calculated by multiplying the total amount 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 applied in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.