GeForce 8400 GS 512MB vs Radeon HD 7970

Intro

Compare those specs to the Radeon HD 7970, which has a core clock speed of 925 MHz and a GDDR5 memory speed of 1375 MHz. It also features a 384-bit bus, and makes use of a 28 nm design. It is comprised of 2048 SPUs, 128 TAUs, and 32 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8400 GS 512MB		40 Watts
Radeon HD 7970		250 Watts
	Difference: 210 Watts (525%)

Memory Bandwidth

The Radeon HD 7970, in theory, should be much faster than the GeForce 8400 GS 512MB overall. (explain)

Radeon HD 7970		264000 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 257600 (4025%)

Texel Rate

The Radeon HD 7970 should be a lot (approximately 2177%) faster with regards to AF than the GeForce 8400 GS 512MB. (explain)

Radeon HD 7970		118400 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 113200 (2177%)

Pixel Rate

The Radeon HD 7970 will be a lot (about 1038%) better at anti-aliasing than the GeForce 8400 GS 512MB, and should be capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 7970		29600 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 27000 (1038%)

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 data (counted in megabytes per second) that can be transferred across the external memory interface within a second. It is calculated by multiplying the card's bus width by its memory speed. If the card has DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, 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 are processed per second. This number is worked out by multiplying the total texture units by the core speed of the chip. The higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

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