Radeon HD 3870 X2 512MB vs Radeon R9 M265X

Intro

Compare those specifications to the Radeon R9 M265X, which uses a 28 nm design. AMD has clocked the core speed at 575 MHz. The GDDR5 RAM runs at a frequency of 1125 MHz on this particular card. 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, the Radeon HD 3870 X2 512MB should perform much faster than the Radeon R9 M265X in general. (explain)

Radeon HD 3870 X2 512MB		115200 MB/sec
Radeon R9 M265X		72000 MB/sec
	Difference: 43200 (60%)

Texel Rate

The Radeon HD 3870 X2 512MB should be a small bit (about 15%) faster with regards to texture filtering than the Radeon R9 M265X. (explain)

Radeon HD 3870 X2 512MB		26400 Mtexels/sec
Radeon R9 M265X		23000 Mtexels/sec
	Difference: 3400 (15%)

Pixel Rate

The Radeon HD 3870 X2 512MB is a lot (approximately 187%) more effective at FSAA than the Radeon R9 M265X, and also should be capable of handling higher screen resolutions more effectively. (explain)

Radeon HD 3870 X2 512MB		26400 Mpixels/sec
Radeon R9 M265X		9200 Mpixels/sec
	Difference: 17200 (187%)

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 MB per second) that can be transferred past the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.