GeForce 825M vs GeForce 840M

Intro

Compare those specifications to the GeForce 840M, which has a core clock frequency of 1029 MHz and a DDR3 memory speed of 1000 MHz. It also uses a 64-bit bus, and uses a 28 nm design. It features 384 SPUs, 24 Texture Address Units, and 8 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 840M		30 Watts
GeForce 825M		33 Watts
	Difference: 3 Watts (10%)

Memory Bandwidth

The GeForce 840M, in theory, should perform a small bit faster than the GeForce 825M overall. (explain)

GeForce 840M		16000 MB/sec
GeForce 825M		14400 MB/sec
	Difference: 1600 (11%)

Texel Rate

The GeForce 840M will be much (more or less 82%) better at anisotropic filtering than the GeForce 825M. (explain)

GeForce 840M		24696 Mtexels/sec
GeForce 825M		13600 Mtexels/sec
	Difference: 11096 (82%)

Pixel Rate

The GeForce 840M should be quite a bit (approximately 21%) better at full screen anti-aliasing than the GeForce 825M, and also will be capable of handling higher screen resolutions while still performing well. (explain)

GeForce 840M		8232 Mpixels/sec
GeForce 825M		6800 Mpixels/sec
	Difference: 1432 (21%)

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 moved over 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 must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels the video card could possibly record to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount 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 is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the max fill rate.