GeForce 840M vs GeForce 9400 GT 256MB

Intro

Compare those specifications to the GeForce 9400 GT 256MB, which comes with core clock speeds of 550 MHz on the GPU, and 400 MHz on the 256 MB of GDDR2 memory. It features 16 SPUs as well as 8 Texture Address Units and 4 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 840M		30 Watts
GeForce 9400 GT 256MB		50 Watts
	Difference: 20 Watts (67%)

Memory Bandwidth

The GeForce 840M should theoretically perform a lot faster than the GeForce 9400 GT 256MB in general. (explain)

GeForce 840M		16000 MB/sec
GeForce 9400 GT 256MB		12800 MB/sec
	Difference: 3200 (25%)

Texel Rate

The GeForce 840M should be much (about 461%) better at texture filtering than the GeForce 9400 GT 256MB. (explain)

GeForce 840M		24696 Mtexels/sec
GeForce 9400 GT 256MB		4400 Mtexels/sec
	Difference: 20296 (461%)

Pixel Rate

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

GeForce 840M		8232 Mpixels/sec
GeForce 9400 GT 256MB		2200 Mpixels/sec
	Difference: 6032 (274%)

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 largest amount of information (counted in megabytes per second) that can be transferred past the external memory interface in one second. It is worked out by multiplying the card's interface width by its memory clock speed. If the card has DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, 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 can be applied per second. This is calculated by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

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