GeForce 820M vs Radeon HD 4770

Intro

Compare all of that to the Radeon HD 4770, which has a core clock speed of 750 MHz and a GDDR5 memory speed of 800 MHz. It also uses a 128-bit memory bus, and uses a 40 nm design. It is comprised of 640(128x5) SPUs, 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

Theoretically, the Radeon HD 4770 should be 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 much (more or less 109%) faster with regards to 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 will be a lot (about 317%) faster with regards to anti-aliasing than the GeForce 820M, and will be capable of handling higher resolutions better. (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: Bandwidth is the largest amount of information (in units of MB per second) that can be moved over the external memory interface in a second. The number is worked out by multiplying the interface width by its memory speed. If it uses DDR type memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.