GeForce 8400 GS 512MB vs GeForce 9400 GT 256MB

Intro

Compare that to the GeForce 9400 GT 256MB, which has clock speeds of 550 MHz on the GPU, and 400 MHz on the 256 MB of GDDR2 RAM. 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 8400 GS 512MB		40 Watts
GeForce 9400 GT 256MB		50 Watts
	Difference: 10 Watts (25%)

Memory Bandwidth

In theory, the GeForce 9400 GT 256MB will be 100% quicker than the GeForce 8400 GS 512MB overall, because of its greater data rate. (explain)

GeForce 9400 GT 256MB		12800 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 6400 (100%)

Texel Rate

The GeForce 8400 GS 512MB will be a little bit (about 18%) faster with regards to texture filtering than the GeForce 9400 GT 256MB. (explain)

GeForce 8400 GS 512MB		5200 Mtexels/sec
GeForce 9400 GT 256MB		4400 Mtexels/sec
	Difference: 800 (18%)

Pixel Rate

The GeForce 8400 GS 512MB is a bit (approximately 18%) faster with regards to FSAA than the GeForce 9400 GT 256MB, and should be able to handle higher resolutions without losing too much performance. (explain)

GeForce 8400 GS 512MB		2600 Mpixels/sec
GeForce 9400 GT 256MB		2200 Mpixels/sec
	Difference: 400 (18%)

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 information (measured in megabytes per second) that can be moved over the external memory interface within a second. It's calculated by multiplying the card's bus width by its memory clock speed. In the case of DDR RAM, it must be multiplied by 2 once again. If it uses 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 high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better this number, 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 maximum amount of pixels the video card could possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.