GeForce 840M vs GeForce 8600 GT 512MB DDR2

Intro

Compare those specifications to the GeForce 8600 GT 512MB DDR2, which makes use of a 80 nm design. nVidia has clocked the core frequency at 540 MHz. The DDR2 memory runs at a speed of 400 MHz on this specific model. It features 32 SPUs along with 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 512MB DDR2		47 Watts
	Difference: 17 Watts (57%)

Memory Bandwidth

In theory, the GeForce 840M should be 25% faster than the GeForce 8600 GT 512MB DDR2 in general, because of its greater data rate. (explain)

GeForce 840M		16000 MB/sec
GeForce 8600 GT 512MB DDR2		12800 MB/sec
	Difference: 3200 (25%)

Texel Rate

The GeForce 840M will be quite a bit (more or less 186%) better at AF than the GeForce 8600 GT 512MB DDR2. (explain)

GeForce 840M		24696 Mtexels/sec
GeForce 8600 GT 512MB DDR2		8640 Mtexels/sec
	Difference: 16056 (186%)

Pixel Rate

If running with a high resolution is important to you, then the GeForce 840M is a better choice, and very much so. (explain)

GeForce 840M		8232 Mpixels/sec
GeForce 8600 GT 512MB DDR2		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: Memory bandwidth is the maximum amount of data (measured in MB per second) that can be transferred over the external memory interface within a second. The number is worked out by multiplying the interface width by its memory clock speed. If the card has DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster 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 can be processed in one second. This is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.