GeForce 8400 GS 512MB vs Radeon HD 6790

Intro

Compare that to the Radeon HD 6790, which comes with GPU core speed of 840 MHz, and 1024 MB of GDDR5 RAM running at 1050 MHz through a 256-bit bus. It also features 800 SPUs, 40 TAUs, and 16 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 6790		150 Watts
	Difference: 110 Watts (275%)

Memory Bandwidth

Performance-wise, the Radeon HD 6790 should theoretically be a lot better than the GeForce 8400 GS 512MB in general. (explain)

Radeon HD 6790		134400 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 128000 (2000%)

Texel Rate

The Radeon HD 6790 will be quite a bit (about 546%) more effective at anisotropic filtering than the GeForce 8400 GS 512MB. (explain)

Radeon HD 6790		33600 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 28400 (546%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 6790 is the winner, by a large margin. (explain)

Radeon HD 6790		13440 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 10840 (417%)

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 information (in units of MB per second) that can be transported across the external memory interface in one second. It is calculated by multiplying the interface width by its memory clock speed. If it uses DDR type RAM, it must be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better 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 can be applied per second. This figure is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The better this number, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

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