GeForce 820M vs Radeon HD 4870 1GB

Intro

Compare those specs to the Radeon HD 4870 1GB, which has a core clock speed of 750 MHz and a GDDR5 memory speed of 900 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 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 4870 1GB		150 Watts
	Difference: 135 Watts (900%)

Memory Bandwidth

In theory, the Radeon HD 4870 1GB will be 620% quicker than the GeForce 820M in general, because of its greater bandwidth. (explain)

Radeon HD 4870 1GB		115200 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 99200 (620%)

Texel Rate

The Radeon HD 4870 1GB will be a lot (more or less 161%) faster with regards to AF than the GeForce 820M. (explain)

Radeon HD 4870 1GB		30000 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 18496 (161%)

Pixel Rate

The Radeon HD 4870 1GB will be quite a bit (about 317%) more effective at AA than the GeForce 820M, and also will be able to handle higher screen resolutions while still performing well. (explain)

Radeon HD 4870 1GB		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 largest amount of data (in units of MB per second) that can be moved over the external memory interface within a second. The number is worked out by multiplying the interface width by its memory speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's 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 texture map elements (texels) that are applied per second. This 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 processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.