Radeon HD 3870 1GB vs Radeon R9 M275X

Intro

Compare all that to the Radeon R9 M275X, which makes use of a 28 nm design. AMD has clocked the core speed at 900 MHz. The GDDR5 RAM runs at a frequency of 1125 MHz on this specific model. 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

Power Consumption (Max TDP)

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

Memory Bandwidth

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

Texel Rate

The Radeon R9 M275X will be much (about 190%) better at 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, not by a very large margin though. (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: Memory bandwidth is the maximum amount of information (measured in MB per second) that can be moved across the external memory interface in one second. It is calculated by multiplying the interface width by its memory speed. If the card has DDR type memory, it must 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, 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 number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better this number, the better the video card will be at handling 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 the video card could possibly write to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.