GeForce 820M vs GeForce GTX 580 3GB

Intro

Compare all that to the GeForce GTX 580 3GB, which comes with clock speeds of 772 MHz on the GPU, and 1002 MHz on the 3072 MB of GDDR5 memory. It features 512 SPUs along with 64 Texture Address Units and 48 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce GTX 580 3GB		244 Watts
	Difference: 229 Watts (1527%)

Memory Bandwidth

Theoretically, the GeForce GTX 580 3GB should perform a lot faster than the GeForce 820M overall. (explain)

GeForce GTX 580 3GB		192384 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 176384 (1102%)

Texel Rate

The GeForce GTX 580 3GB is quite a bit (approximately 329%) better at texture filtering than the GeForce 820M. (explain)

GeForce GTX 580 3GB		49408 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 37904 (329%)

Pixel Rate

The GeForce GTX 580 3GB will be a lot (approximately 1188%) more effective at FSAA than the GeForce 820M, and will be capable of handling higher screen resolutions better. (explain)

GeForce GTX 580 3GB		37056 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 34180 (1188%)

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 maximum amount of data (measured in megabytes per second) that can be transported across the external memory interface in one second. The number is worked out by multiplying the bus width by its memory speed. If it uses DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better 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 number of texture map elements (texels) that are applied in one second. This is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, 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 that the graphics card could possibly record to its local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to get to the max fill rate.