Radeon HD 4790 vs Radeon HD 4850 X2 512MB

Intro

Compare those specifications to the Radeon HD 4850 X2 512MB, which has clock speeds of 625 MHz on the GPU, and 993 MHz on the 512 MB of GDDR3 RAM. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 4850 X2 512MB should theoretically be quite a bit better than the Radeon HD 4790 overall. (explain)

Radeon HD 4850 X2 512MB		127104 MB/sec
Radeon HD 4790		102400 MB/sec
	Difference: 24704 (24%)

Texel Rate

The Radeon HD 4850 X2 512MB will be much (more or less 160%) better at AF than the Radeon HD 4790. (explain)

Radeon HD 4850 X2 512MB		50000 Mtexels/sec
Radeon HD 4790		19200 Mtexels/sec
	Difference: 30800 (160%)

Pixel Rate

The Radeon HD 4850 X2 512MB is quite a bit (about 108%) more effective at full screen anti-aliasing than the Radeon HD 4790, and also should be able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 4850 X2 512MB		20000 Mpixels/sec
Radeon HD 4790		9600 Mpixels/sec
	Difference: 10400 (108%)

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 (measured in megabytes 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 again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied per second. This figure is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher this number, the better the graphics 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 the video card can possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the the core speed of the card. 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 - the lower the bandwidth is, the lower the ability to get to the max fill rate.