Radeon HD 7770 vs Radeon R9 M275X

Intro

Compare those specs to the Radeon R9 M275X, which comes with a core clock frequency of 900 MHz and a GDDR5 memory frequency of 1125 MHz. It also uses a 128-bit bus, and uses a 28 nm design. It features 640 SPUs, 40 TAUs, 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 7770		80 Watts
	Difference: 30 Watts (60%)

Memory Bandwidth

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

Texel Rate

The Radeon HD 7770 will be a little bit (about 11%) more effective at texture filtering than the Radeon R9 M275X. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon R9 M275X		36000 Mtexels/sec
	Difference: 4000 (11%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 7770 is a better choice, though not by far. (explain)

Radeon HD 7770		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: Bandwidth is the maximum amount of information (measured in MB per second) that can be moved over the external memory interface in a second. It is worked out by multiplying the interface width by its memory clock speed. If it uses DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the faster 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 are processed per second. This is worked out by multiplying the total texture units by the core speed of the chip. The higher this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly write to the 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 the card's clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.