GeForce 840M vs GeForce 8600 GT 1GB GDDR3

Intro

Compare that to the GeForce 8600 GT 1GB GDDR3, which features GPU clock speed of 540 MHz, and 1024 MB of GDDR3 memory set to run at 700 MHz through a 128-bit bus. It also is comprised of 32 SPUs, 16 Texture Address Units, and 8 ROPs.

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

The GeForce 8600 GT 1GB GDDR3 should in theory perform much faster than the GeForce 840M in general. (explain)

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

Texel Rate

The GeForce 840M should be a lot (approximately 186%) better at AF 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 is a lot (about 91%) better at FSAA than the GeForce 8600 GT 1GB GDDR3, and also will be able to handle higher screen resolutions without slowing down too much. (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 transported across the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory speed. In the case of DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, 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 number of 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 better the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the most pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.