GeForce 820M vs GeForce GTX 275

Intro

Compare those specs to the GeForce GTX 275, which makes use of a 55 nm design. nVidia has set the core speed at 633 MHz. The GDDR3 RAM is set to run at a speed of 1134 MHz on this particular model. It features 240 SPUs along with 80 TAUs and 28 ROPs.

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

In theory, the GeForce GTX 275 should perform quite a bit faster than the GeForce 820M overall. (explain)

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

Texel Rate

The GeForce GTX 275 will be quite a bit (more or less 340%) more effective at texture filtering than the GeForce 820M. (explain)

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

Pixel Rate

The GeForce GTX 275 should be much (approximately 516%) faster with regards to FSAA than the GeForce 820M, and capable of handling higher resolutions without losing too much performance. (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: Memory bandwidth is the maximum amount of information (counted in MB per second) that can be transported past the external memory interface in a second. It is calculated by multiplying the bus width by the speed of its memory. If it uses DDR RAM, it should be multiplied by 2 again. If it uses 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 high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed per second. This is worked out by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, the better the video card will be at 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 the video card could possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.