Radeon HD 4870 X2 vs Radeon R9 M265X

Intro

Compare those specs to the Radeon R9 M265X, which comes with a GPU core clock speed of 575 MHz, and 2048 MB of GDDR5 RAM set to run at 1125 MHz through a 128-bit bus. It also is comprised of 640 Stream Processors, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Theoretically, the Radeon HD 4870 X2 should be a lot faster than the Radeon R9 M265X overall. (explain)

Radeon HD 4870 X2		230400 MB/sec
Radeon R9 M265X		72000 MB/sec
	Difference: 158400 (220%)

Texel Rate

The Radeon HD 4870 X2 will be quite a bit (about 161%) more effective at texture filtering than the Radeon R9 M265X. (explain)

Radeon HD 4870 X2		60000 Mtexels/sec
Radeon R9 M265X		23000 Mtexels/sec
	Difference: 37000 (161%)

Pixel Rate

The Radeon HD 4870 X2 should be a lot (more or less 161%) better at FSAA than the Radeon R9 M265X, and also will be capable of handling higher screen resolutions while still performing well. (explain)

Radeon HD 4870 X2		24000 Mpixels/sec
Radeon R9 M265X		9200 Mpixels/sec
	Difference: 14800 (161%)

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 max amount of information (in units of MB per second) that can be transferred across the external memory interface within a second. It's worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the 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 are applied per second. This figure is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to the local memory in a 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 - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.