GeForce 830M vs GeForce 840M

Intro

Compare those specs to the GeForce 840M, which uses a 28 nm design. nVidia has clocked the core frequency at 1029 MHz. The DDR3 memory runs at a speed of 1000 MHz on this card. 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

The GeForce 840M should theoretically perform a bit faster than the GeForce 830M overall. (explain)

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

Texel Rate

The GeForce 840M should be a lot (about 50%) more effective at 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 exactly the same pixel fill rate, so in theory they should perform 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: Memory bandwidth is the maximum amount of data (in units of MB per second) that can be moved across the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory speed. If it uses DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. 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 amount of texture map elements (texels) that can be processed per second. This figure is worked out by multiplying the total number of texture units of the card by the core speed of the chip. The higher the texel rate, the better the 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 maximum amount of pixels the graphics card can possibly write to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of 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 fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.