GeForce 820M vs Radeon HD 4770

Intro

Compare those specs to the Radeon HD 4770, which uses a 40 nm design. AMD has clocked the core frequency at 750 MHz. The GDDR5 memory is set to run at a speed of 800 MHz on this specific model. It features 640(128x5) SPUs as well as 32 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
Radeon HD 4770		80 Watts
	Difference: 65 Watts (433%)

Memory Bandwidth

The Radeon HD 4770, in theory, should perform much faster than the GeForce 820M overall. (explain)

Radeon HD 4770		51200 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 35200 (220%)

Texel Rate

The Radeon HD 4770 is a lot (about 109%) better at anisotropic filtering than the GeForce 820M. (explain)

Radeon HD 4770		24000 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 12496 (109%)

Pixel Rate

The Radeon HD 4770 should be much (about 317%) more effective at full screen anti-aliasing than the GeForce 820M, and should be able to handle higher resolutions while still performing well. (explain)

Radeon HD 4770		12000 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 9124 (317%)

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 (counted in megabytes per second) that can be transferred past the external memory interface within a second. The number is calculated by multiplying the card's interface width by its memory clock speed. If it uses DDR type RAM, the result should be multiplied by 2 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, 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 figure is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.