GeForce 8400 GS 512MB vs Radeon HD 7990

Intro

Compare all that to the Radeon HD 7990, which features core speeds of 950 MHz on the GPU, and 1500 MHz on the 3072 MB of GDDR5 memory. It features 2048 SPUs along with 128 TAUs 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 7990		375 Watts
	Difference: 335 Watts (838%)

Memory Bandwidth

The Radeon HD 7990, in theory, should perform quite a bit faster than the GeForce 8400 GS 512MB in general. (explain)

Radeon HD 7990		576000 MB/sec
GeForce 8400 GS 512MB		6400 MB/sec
	Difference: 569600 (8900%)

Texel Rate

The Radeon HD 7990 will be a lot (approximately 4577%) faster with regards to texture filtering than the GeForce 8400 GS 512MB. (explain)

Radeon HD 7990		243200 Mtexels/sec
GeForce 8400 GS 512MB		5200 Mtexels/sec
	Difference: 238000 (4577%)

Pixel Rate

The Radeon HD 7990 should be a lot (more or less 2238%) faster with regards to FSAA than the GeForce 8400 GS 512MB, and will be able to handle higher screen resolutions without slowing down too much. (explain)

Radeon HD 7990		60800 Mpixels/sec
GeForce 8400 GS 512MB		2600 Mpixels/sec
	Difference: 58200 (2238%)

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.

One or more cards in this comparison are multi-core. This means that their bandwidth, texel and pixel rates are theoretically doubled - this does not mean the card will actually perform twice as fast, but only that it should in theory be able to. Actual game benchmarks will give a more accurate idea of what it's capable of.

Price Comparison

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of data (counted in megabytes per second) that can be transported over the external memory interface in one second. The number is calculated by multiplying the interface width by its memory speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher 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 texture map elements (texels) that are applied per second. This is calculated by multiplying the total number of texture units by the core clock speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly write to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as 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 of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.