GeForce 8400 GS 512MB vs Radeon HD 7870

Intro

Compare all of that to the Radeon HD 7870, which features core speeds of 1000 MHz on the GPU, and 1200 MHz on the 2048 MB of GDDR5 memory. It features 1280 SPUs along with 80 Texture Address Units and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8400 GS 512MB		40 Watts
Radeon HD 7870		175 Watts
	Difference: 135 Watts (338%)

Memory Bandwidth

In theory, the Radeon HD 7870 will be 2300% quicker than the GeForce 8400 GS 512MB in general, because of its higher data rate. (explain)

Radeon HD 7870		153600 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 147200 (2300%)

Texel Rate

The Radeon HD 7870 should be quite a bit (about 1438%) faster with regards to AF than the GeForce 8400 GS 512MB. (explain)

Radeon HD 7870		80000 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 74800 (1438%)

Pixel Rate

If running with high levels of AA is important to you, then the Radeon HD 7870 is superior to the GeForce 8400 GS 512MB, by a large margin. (explain)

Radeon HD 7870		32000 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 29400 (1131%)

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 transported past the external memory interface in one second. It is worked out by multiplying the bus width by its memory clock speed. If it uses DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better 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 number of texture map elements (texels) that can be applied per second. This figure is worked out by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of ROPs by the clock speed of the card. 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 many other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.