GeForce 825M vs GeForce 840M

Intro

Compare those specifications to the GeForce 840M, which has core speeds of 1029 MHz on the GPU, and 1000 MHz on the 2048 MB of DDR3 RAM. It features 384 SPUs as well as 24 Texture Address Units and 8 Rasterization Operator 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

In theory, the GeForce 840M should perform a little 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 quite a bit (about 82%) more effective at AF than the GeForce 825M. (explain)

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

Pixel Rate

The GeForce 840M will be quite a bit (more or less 21%) better at anti-aliasing than the GeForce 825M, and also will be able to handle higher screen resolutions without slowing down too much. (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: Bandwidth is the largest amount of data (counted in MB per second) that can be moved across the external memory interface in one second. It is calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied in one second. This number is worked out by multiplying the total texture units by the core clock speed of the chip. The higher this number, the better the graphics 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 video card could possibly write to the local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.