GeForce 840M vs GeForce 9400 GT 256MB

Intro

Compare all that to the GeForce 9400 GT 256MB, which has a clock frequency of 550 MHz and a GDDR2 memory frequency of 400 MHz. It also uses a 128-bit bus, and uses a 65 nm design. It features 16 SPUs, 8 Texture Address Units, and 4 ROPs.

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 be quite a bit 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 will be a lot (approximately 461%) faster with regards to 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 max amount of data (measured in megabytes per second) that can be transferred across the external memory interface in one second. The number is calculated by multiplying the interface width by its memory clock speed. In the case of DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better 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 can be applied in one second. This figure 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 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 that the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core speed of the card. 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 fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.