Radeon HD 3870 X2 1GB vs Radeon R9 M275X

Intro

Compare that to the Radeon R9 M275X, which has core clock speeds of 900 MHz on the GPU, and 1125 MHz on the 2048 MB of GDDR5 RAM. It features 640 SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically speaking, the Radeon HD 3870 X2 1GB will be 100% quicker than the Radeon R9 M275X in general, because of its greater bandwidth. (explain)

Radeon HD 3870 X2 1GB		144128 MB/sec
Radeon R9 M275X		72000 MB/sec
	Difference: 72128 (100%)

Texel Rate

The Radeon R9 M275X should be a lot (about 36%) better at AF than the Radeon HD 3870 X2 1GB. (explain)

Radeon R9 M275X		36000 Mtexels/sec
Radeon HD 3870 X2 1GB		26400 Mtexels/sec
	Difference: 9600 (36%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon HD 3870 X2 1GB is superior to the Radeon R9 M275X, by a large margin. (explain)

Radeon HD 3870 X2 1GB		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 maximum amount of information (counted in megabytes per second) that can be transferred past the external memory interface within a second. It is calculated by multiplying the bus width by its memory clock speed. In the case of DDR memory, it should be multiplied by 2 once 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 texture map elements (texels) that are applied per second. This number is worked out by multiplying the total texture units by the core speed of the chip. The better the texel rate, the better the video 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 most pixels that the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of ROPs by the the core clock speed. 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, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.