GeForce 830M vs GeForce 840M

Intro

Compare those specs to the GeForce 840M, which has a core clock speed of 1029 MHz and a DDR3 memory speed of 1000 MHz. It also features a 64-bit bus, and makes use of a 28 nm design. It is comprised of 384 SPUs, 24 Texture Address Units, and 8 Raster Operation 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 is 11% faster than the GeForce 830M in general, due to its greater data rate. (explain)

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

Texel Rate

The GeForce 840M is much (approximately 50%) faster with regards to anisotropic 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 fill rate, so in theory they should perform equally good at at anti-aliasing, 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 max amount of information (measured in MB per second) that can be transferred over the external memory interface in a second. It's calculated by multiplying the card's bus width by its memory speed. If the card has DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied in one second. This figure is worked out by multiplying the total amount of texture units by the core speed of the chip. The higher this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.