GeForce 830M vs GeForce 840M

Intro

Compare all that to the GeForce 840M, which has core clock speeds of 1029 MHz on the GPU, and 1000 MHz on the 2048 MB of DDR3 memory. It features 384 SPUs along with 24 Texture Address Units and 8 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 830M		25 Watts
GeForce 840M		30 Watts
	Difference: 5 Watts (20%)

Memory Bandwidth

In theory, the GeForce 840M should be 11% faster than the GeForce 830M in general, because of its higher bandwidth. (explain)

GeForce 840M		16000 MB/sec
GeForce 830M		14400 MB/sec
	Difference: 1600 (11%)

Texel Rate

The GeForce 840M will be much (approximately 50%) faster with regards to texture filtering than the GeForce 830M. (explain)

GeForce 840M		24696 Mtexels/sec
GeForce 830M		16464 Mtexels/sec
	Difference: 8232 (50%)

Pixel Rate

Both cards have the exact same pixel rate, so theoretically they should be equally good at at FSAA, and be able to handle the same resolutions. (explain)

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 (in units of megabytes per second) that can be transported past the external memory interface in a second. It's calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR memory, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, 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 processed per second. This figure is calculated by multiplying the total texture units of the card by the core clock speed of the chip. The higher this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.