Radeon HD 4870 2GB vs Radeon R9 M275X

Intro

Compare that to the Radeon R9 M275X, which comes with clock speeds of 900 MHz on the GPU, and 1125 MHz on the 2048 MB of GDDR5 RAM. It features 640 SPUs along with 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 4870 2GB		150 Watts
	Difference: 100 Watts (200%)

Memory Bandwidth

The Radeon HD 4870 2GB, in theory, should be much faster than the Radeon R9 M275X in general. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon R9 M275X		72000 MB/sec
	Difference: 43200 (60%)

Texel Rate

The Radeon R9 M275X should be a bit (approximately 20%) faster with regards to AF than the Radeon HD 4870 2GB. (explain)

Radeon R9 M275X		36000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 6000 (20%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon R9 M275X is the winner, but only just. (explain)

Radeon R9 M275X		14400 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 2400 (20%)

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 (counted in MB per second) that can be transported across the external memory interface within a second. The number is calculated by multiplying the card's bus width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This number is worked out by multiplying the total texture units of the card 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 a second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.