GeForce 825M vs GeForce 840M

Intro

Compare those specifications to the GeForce 840M, which uses a 28 nm design. nVidia has set the core frequency at 1029 MHz. The DDR3 memory runs at a frequency of 1000 MHz on this specific card. It features 384 SPUs along with 24 TAUs and 8 ROPs.

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

As far as performance goes, the GeForce 840M should theoretically be a little bit better than the GeForce 825M overall. (explain)

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

Texel Rate

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

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

Pixel Rate

The GeForce 840M is quite a bit (approximately 21%) more effective at anti-aliasing than the GeForce 825M, and should be able to handle higher 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: Bandwidth is the maximum amount of data (measured in MB per second) that can be moved past the external memory interface in one second. It's calculated by multiplying the card's interface width by its memory clock speed. If the card has DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, 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 texture map elements (texels) that are processed in one second. This number is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The higher 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 maximum number of pixels that the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.