GeForce 8400 GS 512MB vs Radeon HD 6790

Intro

Compare those specs to the Radeon HD 6790, which features GPU clock speed of 840 MHz, and 1024 MB of GDDR5 RAM running at 1050 MHz through a 256-bit bus. It also is made up of 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

Theoretically speaking, the Radeon HD 6790 should be a lot faster than the GeForce 8400 GS 512MB overall. (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 a lot (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

The Radeon HD 6790 should be a lot (about 417%) better at full screen anti-aliasing than the GeForce 8400 GS 512MB, and also will be capable of handling higher screen resolutions more effectively. (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 data (measured in megabytes per second) that can be moved over the external memory interface within a second. It is calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip could possibly write to its local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.