Radeon HD 7770 vs Radeon R9 M275X

Intro

Compare that to the Radeon R9 M275X, which comes with core speeds of 900 MHz on the GPU, and 1125 MHz on the 2048 MB of GDDR5 RAM. It features 640 SPUs as well as 40 TAUs and 16 Rasterization Operator 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 exactly the same memory bandwidth, so in theory they should perform exactly the same. (explain)

Texel Rate

The Radeon HD 7770 will be a little bit (more or less 11%) better at anisotropic filtering than the Radeon R9 M275X. (explain)

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

Pixel Rate

The Radeon HD 7770 should be a bit (approximately 11%) more effective at anti-aliasing than the Radeon R9 M275X, and also will be able to handle higher screen resolutions better. (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: Memory bandwidth is the largest amount of data (measured in MB per second) that can be transported over the external memory interface in a second. It is worked out by multiplying the bus width by its memory clock speed. In the case of DDR RAM, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better 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 number of texture map elements (texels) that can be processed per second. This figure is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the most pixels the video card could possibly write to the local memory per second - measured in millions of pixels per second. The figure is worked out 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, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.