GeForce 840M vs GeForce 8600 GT 1GB GDDR3

Intro

Compare those specifications to the GeForce 8600 GT 1GB GDDR3, which has a clock frequency of 540 MHz and a GDDR3 memory speed of 700 MHz. It also makes use of a 128-bit bus, and uses a 80 nm design. It is comprised of 32 SPUs, 16 Texture Address Units, and 8 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 840M		30 Watts
GeForce 8600 GT 1GB GDDR3		47 Watts
	Difference: 17 Watts (57%)

Memory Bandwidth

Theoretically speaking, the GeForce 8600 GT 1GB GDDR3 will be 40% quicker than the GeForce 840M in general, because of its greater bandwidth. (explain)

GeForce 8600 GT 1GB GDDR3		22400 MB/sec
GeForce 840M		16000 MB/sec
	Difference: 6400 (40%)

Texel Rate

The GeForce 840M will be a lot (about 186%) faster with regards to texture filtering than the GeForce 8600 GT 1GB GDDR3. (explain)

GeForce 840M		24696 Mtexels/sec
GeForce 8600 GT 1GB GDDR3		8640 Mtexels/sec
	Difference: 16056 (186%)

Pixel Rate

The GeForce 840M should be a lot (more or less 91%) faster with regards to anti-aliasing than the GeForce 8600 GT 1GB GDDR3, and should be able to handle higher screen resolutions better. (explain)

GeForce 840M		8232 Mpixels/sec
GeForce 8600 GT 1GB GDDR3		4320 Mpixels/sec
	Difference: 3912 (91%)

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 (measured in megabytes per second) that can be moved over the external memory interface within a second. It is calculated by multiplying the card's interface width by its memory speed. If the card has DDR memory, the result should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This number is calculated 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.