Radeon HD 3870 1GB vs Radeon R9 M270X

Intro

Compare those specifications to the Radeon R9 M270X, which makes use of a 28 nm design. AMD has clocked the core speed at 725 MHz. The GDDR5 RAM works at a frequency of 1125 MHz on this model. 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

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

Texel Rate

The Radeon R9 M270X is much (more or less 134%) more effective at anisotropic filtering than the Radeon HD 3870 1GB. (explain)

Radeon R9 M270X		29000 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 16600 (134%)

Pixel Rate

The Radeon HD 3870 1GB will be just a bit (about 7%) better at full screen anti-aliasing than the Radeon R9 M270X, and also able to handle higher screen resolutions better. (explain)

Radeon HD 3870 1GB		12400 Mpixels/sec
Radeon R9 M270X		11600 Mpixels/sec
	Difference: 800 (7%)

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 largest amount of data (in units of megabytes per second) that can be moved past the external memory interface in a second. It's calculated by multiplying the bus width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the better 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 texture map elements (texels) that are applied in one second. This figure is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.