GeForce 8800 GTS (G80) 640MB vs Radeon HD 4850 X2 512MB

Intro

Compare those specs to the Radeon HD 4850 X2 512MB, which makes use of a 55 nm design. AMD has clocked the core frequency at 625 MHz. The GDDR3 memory runs at a frequency of 993 MHz on this model. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8800 GTS (G80) 640MB		143 Watts
Radeon HD 4850 X2 512MB		250 Watts
	Difference: 107 Watts (75%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4850 X2 512MB should perform quite a bit faster than the GeForce 8800 GTS (G80) 640MB overall. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
GeForce 8800 GTS (G80) 640MB		63360 MB/sec
	Difference: 63744 (101%)

Texel Rate

The Radeon HD 4850 X2 512MB should be quite a bit (approximately 103%) better at anisotropic filtering than the GeForce 8800 GTS (G80) 640MB. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
GeForce 8800 GTS (G80) 640MB		24624 Mtexels/sec
	Difference: 25376 (103%)

Pixel Rate

The Radeon HD 4850 X2 512MB should be quite a bit (about 95%) faster with regards to AA than the GeForce 8800 GTS (G80) 640MB, and also will be able to handle higher screen resolutions better. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
GeForce 8800 GTS (G80) 640MB		10260 Mpixels/sec
	Difference: 9740 (95%)

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 information (in units of megabytes per second) that can be transported over the external memory interface in one second. It's calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to its local memory in one second - measured in millions of pixels per second. The figure is worked out 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 filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.