Radeon HD 3870 1GB vs Radeon R9 M270X

Intro

Compare those specifications to the Radeon R9 M270X, which has GPU core speed of 725 MHz, and 2048 MB of GDDR5 RAM set to run at 1125 MHz through a 128-bit bus. It also is made up of 640 SPUs, 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 memory bandwidth, so in theory they should have identical performance. (explain)

Texel Rate

The Radeon R9 M270X is a lot (approximately 134%) more effective at AF 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 a small bit (about 7%) better at full screen anti-aliasing than the Radeon R9 M270X, and also will be capable of handling 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 maximum amount of data (measured in megabytes per second) that can be moved past the external memory interface within a second. It is worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per second. This is calculated 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 handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.