GeForce 820M vs GeForce GTS 250 512MB

Intro

Compare all that to the GeForce GTS 250 512MB, which has a core clock frequency of 738 MHz and a GDDR3 memory speed of 1100 MHz. It also uses a 256-bit bus, and uses a 65/55 nm design. It is comprised of 128 SPUs, 64 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 820M		15 Watts
GeForce GTS 250 512MB		145 Watts
	Difference: 130 Watts (867%)

Memory Bandwidth

Theoretically speaking, the GeForce GTS 250 512MB will be 340% faster than the GeForce 820M in general, because of its greater data rate. (explain)

GeForce GTS 250 512MB		70400 MB/sec
GeForce 820M		16000 MB/sec
	Difference: 54400 (340%)

Texel Rate

The GeForce GTS 250 512MB should be quite a bit (more or less 311%) more effective at texture filtering than the GeForce 820M. (explain)

GeForce GTS 250 512MB		47232 Mtexels/sec
GeForce 820M		11504 Mtexels/sec
	Difference: 35728 (311%)

Pixel Rate

If using high levels of AA is important to you, then the GeForce GTS 250 512MB is the winner, by a large margin. (explain)

GeForce GTS 250 512MB		11808 Mpixels/sec
GeForce 820M		2876 Mpixels/sec
	Difference: 8932 (311%)

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 (measured in MB per second) that can be transferred across the external memory interface in a second. It's worked out by multiplying the card's interface width by its memory speed. In the case of DDR type memory, it must be multiplied by 2 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 amount of texture map elements (texels) that are applied in one second. This figure is worked out by multiplying the total 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 per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.