Radeon HD 4790 vs Radeon HD 4850 X2 512MB

Intro

Compare those specs to the Radeon HD 4850 X2 512MB, which uses 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 particular model. It features 800(160x5) SPUs along with 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Memory Bandwidth

Performance-wise, the Radeon HD 4850 X2 512MB should in theory be quite a bit better than the Radeon HD 4790 in general. (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 is quite a bit (approximately 160%) better at anisotropic filtering 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

If using lots of anti-aliasing is important to you, then the Radeon HD 4850 X2 512MB is superior to the Radeon HD 4790, by far. (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 max amount of data (in units of MB per second) that can be transferred over the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory speed. If the card has DDR type RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This number 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 video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to its local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour ROPs by the the core clock speed. 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 lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.