GeForce 8400 GS 512MB vs Radeon HD 7790

Intro

Compare those specs to the Radeon HD 7790, which features a core clock speed of 1000 MHz and a GDDR5 memory speed of 1500 MHz. It also uses a 128-bit bus, and makes use of a 28 nm design. It is comprised of 896 SPUs, 56 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8400 GS 512MB		40 Watts
Radeon HD 7790		85 Watts
	Difference: 45 Watts (113%)

Memory Bandwidth

In theory, the Radeon HD 7790 should be much faster than the GeForce 8400 GS 512MB overall. (explain)

Radeon HD 7790		96000 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 89600 (1400%)

Texel Rate

The Radeon HD 7790 is much (about 977%) better at texture filtering than the GeForce 8400 GS 512MB. (explain)

Radeon HD 7790		56000 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 50800 (977%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 7790 is the winner, and very much so. (explain)

Radeon HD 7790		16000 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 13400 (515%)

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 (in units of MB per second) that can be transported over the external memory interface in a second. It is calculated by multiplying the card's interface width by its memory clock speed. In the case of DDR type RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, 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 number is calculated by multiplying the total amount of texture units of the card by the core speed of the chip. The better this number, the better the video 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 card could possibly write to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.