GeForce 820M vs GeForce GTX 275

Intro

Compare those specifications to the GeForce GTX 275, which features GPU core speed of 633 MHz, and 896 MB of GDDR3 RAM running at 1134 MHz through a 448-bit bus. It also is made up of 240 Stream Processors, 80 Texture Address Units, and 28 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce GTX 275		219 Watts
	Difference: 204 Watts (1360%)

Memory Bandwidth

Theoretically speaking, the GeForce GTX 275 will be 694% faster than the GeForce 820M in general, because of its higher data rate. (explain)

GeForce GTX 275		127008 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 111008 (694%)

Texel Rate

The GeForce GTX 275 should be much (about 340%) faster with regards to texture filtering than the GeForce 820M. (explain)

GeForce GTX 275		50640 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 39136 (340%)

Pixel Rate

If running with a high screen resolution is important to you, then the GeForce GTX 275 is a better choice, by far. (explain)

GeForce GTX 275		17724 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 14848 (516%)

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 data (measured in MB per second) that can be transported past the external memory interface in one second. It is worked out by multiplying the card's bus width by the speed of its memory. In the case of DDR memory, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.