GeForce 820M vs GeForce 9400 GT 256MB

Intro

Compare those specifications to the GeForce 9400 GT 256MB, which has a clock speed of 550 MHz and a GDDR2 memory frequency of 400 MHz. It also features a 128-bit bus, and uses a 65 nm design. It is comprised of 16 SPUs, 8 TAUs, and 4 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce 9400 GT 256MB		50 Watts
	Difference: 35 Watts (233%)

Memory Bandwidth

The GeForce 820M, in theory, should perform quite a bit faster than the GeForce 9400 GT 256MB in general. (explain)

GeForce 820M		16000 MB/sec
GeForce 9400 GT 256MB		12800 MB/sec
	Difference: 3200 (25%)

Texel Rate

The GeForce 820M is much (approximately 161%) more effective at AF than the GeForce 9400 GT 256MB. (explain)

GeForce 820M		11504 Mtexels/sec
GeForce 9400 GT 256MB		4400 Mtexels/sec
	Difference: 7104 (161%)

Pixel Rate

The GeForce 820M should be a lot (about 31%) better at AA than the GeForce 9400 GT 256MB, and also should be able to handle higher screen resolutions better. (explain)

GeForce 820M		2876 Mpixels/sec
GeForce 9400 GT 256MB		2200 Mpixels/sec
	Difference: 676 (31%)

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 in a second. It's calculated by multiplying the interface width by its memory clock speed. If the card has DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total texture units of the card by the core speed of the chip. The better this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

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