GeForce 820M vs GeForce 825M

Intro

Compare those specs to the GeForce 825M, which has a core clock speed of 850 MHz and a DDR3 memory frequency of 900 MHz. It also features a 64-bit memory bus, and makes use of a 28 nm design. It is made up of 384 SPUs, 16 Texture Address Units, and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce 825M		33 Watts
	Difference: 18 Watts (120%)

Memory Bandwidth

The GeForce 820M should theoretically be just a bit faster than the GeForce 825M in general. (explain)

GeForce 820M		16000 MB/sec
GeForce 825M		14400 MB/sec
	Difference: 1600 (11%)

Texel Rate

The GeForce 825M will be just a bit (approximately 18%) more effective at AF than the GeForce 820M. (explain)

GeForce 825M		13600 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 2096 (18%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the GeForce 825M is superior to the GeForce 820M, by a large margin. (explain)

GeForce 825M		6800 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 3924 (136%)

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 data (counted in megabytes per second) that can be transported across the external memory interface within a second. It's worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are processed in one second. This is worked out by multiplying the total amount of 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 per second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the card's clock speed. 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 many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.