Radeon HD 4870 2GB vs Radeon R9 M380

Intro

Compare those specifications to the Radeon R9 M380, which comes with a core clock frequency of 1000 MHz and a GDDR5 memory speed of 1500 MHz. It also uses a 128-bit memory bus, and makes use of a 28 nm design. It is made up of 640 SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 4870 2GB will be 20% quicker than the Radeon R9 M380 overall, because of its higher bandwidth. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon R9 M380		96000 MB/sec
	Difference: 19200 (20%)

Texel Rate

The Radeon R9 M380 will be quite a bit (more or less 33%) better at AF than the Radeon HD 4870 2GB. (explain)

Radeon R9 M380		40000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 10000 (33%)

Pixel Rate

If running with a high resolution is important to you, then the Radeon R9 M380 is a better choice, and very much so. (explain)

Radeon R9 M380		16000 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 4000 (33%)

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 past the external memory interface within a second. It's calculated by multiplying the interface width by its memory speed. If the card has DDR type 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 AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total texture units by the core clock speed of the chip. The higher this number, the better the graphics 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 that the graphics chip could possibly record to the local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Render Output Units by the the core 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 rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.