Radeon HD 4770 vs Radeon R5 M255

Intro

Compare those specifications to the Radeon R5 M255, which comes with a clock speed of 940 MHz and a DDR3 memory frequency of 1000 MHz. It also uses a 64-bit memory bus, and makes use of a 28 nm design. It is made up of 320 SPUs, 20 Texture Address Units, and 8 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

In theory, the Radeon HD 4770 should be 220% faster than the Radeon R5 M255 in general, because of its higher bandwidth. (explain)

Radeon HD 4770		51200 MB/sec
Radeon R5 M255		16000 MB/sec
	Difference: 35200 (220%)

Texel Rate

The Radeon HD 4770 is much (about 28%) better at AF than the Radeon R5 M255. (explain)

Radeon HD 4770		24000 Mtexels/sec
Radeon R5 M255		18800 Mtexels/sec
	Difference: 5200 (28%)

Pixel Rate

The Radeon HD 4770 should be a lot (approximately 60%) more effective at full screen anti-aliasing than the Radeon R5 M255, and should be able to handle higher resolutions without losing too much performance. (explain)

Radeon HD 4770		12000 Mpixels/sec
Radeon R5 M255		7520 Mpixels/sec
	Difference: 4480 (60%)

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 max amount of information (in units of megabytes per second) that can be transferred past the external memory interface within a second. It is worked out by multiplying the bus width by its memory speed. In the case of DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied per second. This figure is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.