Radeon HD 4890 1GB vs Radeon R9 M275X

Intro

Compare those specs to the Radeon R9 M275X, which comes with a clock speed of 900 MHz and a GDDR5 memory speed of 1125 MHz. It also uses a 128-bit bus, and makes use of a 28 nm design. It features 640 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon R9 M275X		50 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 140 Watts (280%)

Memory Bandwidth

The Radeon HD 4890 1GB, in theory, should be much faster than the Radeon R9 M275X overall. (explain)

Radeon HD 4890 1GB		124800 MB/sec
Radeon R9 M275X		72000 MB/sec
	Difference: 52800 (73%)

Texel Rate

The Radeon HD 4890 1GB is just a bit (more or less 11%) more effective at anisotropic filtering than the Radeon R9 M275X. (explain)

Radeon HD 4890 1GB		40000 Mtexels/sec
Radeon R9 M275X		36000 Mtexels/sec
	Difference: 4000 (11%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 4890 1GB is superior to the Radeon R9 M275X, but it probably won't make a huge difference. (explain)

Radeon HD 4890 1GB		16000 Mpixels/sec
Radeon R9 M275X		14400 Mpixels/sec
	Difference: 1600 (11%)

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 data (measured in megabytes per second) that can be transported over the external memory interface within a second. It's calculated by multiplying the interface width by its memory speed. In the case of DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, 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 number is worked out by multiplying the total texture units by the core speed of the chip. The better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. Pixel rate 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 drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.