Radeon HD 3870 1GB vs Radeon R9 M275X

Intro

Compare those specs to the Radeon R9 M275X, which makes use of a 28 nm design. AMD has set the core frequency at 900 MHz. The GDDR5 memory is set to run at a frequency of 1125 MHz on this card. It features 640 SPUs as well as 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M275X		50 Watts
Radeon HD 3870 1GB		106 Watts
	Difference: 56 Watts (112%)

Memory Bandwidth

Both cards have the exact same memory bandwidth, so in theory they should perform exactly the same. (explain)

Texel Rate

The Radeon R9 M275X should be much (approximately 190%) faster with regards to anisotropic filtering than the Radeon HD 3870 1GB. (explain)

Radeon R9 M275X		36000 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 23600 (190%)

Pixel Rate

If using a high screen resolution is important to you, then the Radeon R9 M275X is superior to the Radeon HD 3870 1GB, though not by far. (explain)

Radeon R9 M275X		14400 Mpixels/sec
Radeon HD 3870 1GB		12400 Mpixels/sec
	Difference: 2000 (16%)

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 (measured in megabytes per second) that can be moved over the external memory interface in one second. It's calculated by multiplying the card's bus width by its memory speed. If the card has DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Render Output Units by the the core clock speed. 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 bandwidth is, the lower the potential to reach the maximum fill rate.