GeForce 820M vs GeForce 9800 GX2

Intro

Compare those specs to the GeForce 9800 GX2, which makes use of a 65 nm design. nVidia has clocked the core speed at 600 MHz. The GDDR3 RAM runs at a frequency of 1000 MHz on this card. It features 128 SPUs along with 64 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce 9800 GX2		197 Watts
	Difference: 182 Watts (1213%)

Memory Bandwidth

Theoretically, the GeForce 9800 GX2 should perform a lot faster than the GeForce 820M overall. (explain)

GeForce 9800 GX2		128000 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 112000 (700%)

Texel Rate

The GeForce 9800 GX2 should be a lot (about 568%) better at AF than the GeForce 820M. (explain)

GeForce 9800 GX2		76800 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 65296 (568%)

Pixel Rate

The GeForce 9800 GX2 will be much (about 568%) better at full screen anti-aliasing than the GeForce 820M, and also should be capable of handling higher screen resolutions without slowing down too much. (explain)

GeForce 9800 GX2		19200 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 16324 (568%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the max amount of information (in units of megabytes per second) that can be transported across the external memory interface in one second. The number is calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR memory, the result should be multiplied by 2 once 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 higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the clock speed of the card. 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, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.