Radeon HD 3870 1GB vs Radeon R9 M265X

Intro

Compare those specs to the Radeon R9 M265X, which has clock speeds of 575 MHz on the GPU, and 1125 MHz on the 2048 MB of GDDR5 memory. It features 640 SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Both cards have the exact same bandwidth, so theoretically they should perform the same. (explain)

Texel Rate

The Radeon R9 M265X will be quite a bit (more or less 85%) more effective at AF than the Radeon HD 3870 1GB. (explain)

Radeon R9 M265X		23000 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 10600 (85%)

Pixel Rate

The Radeon HD 3870 1GB should be a lot (about 35%) more effective at anti-aliasing than the Radeon R9 M265X, and able to handle higher screen resolutions better. (explain)

Radeon HD 3870 1GB		12400 Mpixels/sec
Radeon R9 M265X		9200 Mpixels/sec
	Difference: 3200 (35%)

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.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the max amount of information (in units of MB per second) that can be transferred over the external memory interface in one second. The number is worked out by multiplying the interface width by its memory speed. If the card has DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly write to the 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 the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.