Radeon HD 3870 X2 512MB vs Radeon R9 M275X

Intro

Compare all of that to the Radeon R9 M275X, which comes with a clock frequency of 900 MHz and a GDDR5 memory frequency of 1125 MHz. It also makes use of a 128-bit memory bus, and uses a 28 nm design. It features 640 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 3870 X2 512MB should in theory be quite a bit better than the Radeon R9 M275X overall. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon R9 M275X		72000 MB/sec
	Difference: 43200 (60%)

Texel Rate

The Radeon R9 M275X will be a lot (approximately 36%) better at anisotropic filtering than the Radeon HD 3870 X2 512MB. (explain)

Radeon R9 M275X		36000 Mtexels/sec
Radeon HD 3870 X2 512MB		26400 Mtexels/sec
	Difference: 9600 (36%)

Pixel Rate

The Radeon HD 3870 X2 512MB will be much (about 83%) better at AA than the Radeon R9 M275X, and will be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon R9 M275X		14400 Mpixels/sec
	Difference: 12000 (83%)

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 largest amount of information (in units of megabytes per second) that can be transported across the external memory interface within a second. It is calculated by multiplying the interface width by the speed of its memory. If it uses DDR memory, it must 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 number of texture map elements (texels) that can be processed per second. This is worked out by multiplying the total 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 applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.