Radeon HD 4850 X2 1GB vs Radeon HD 7770

Intro

Compare that to the Radeon HD 7770, which makes use of a 28 nm design. AMD has clocked the core speed at 1000 MHz. The GDDR5 memory is set to run at a speed of 1125 MHz on this card. It features 640 SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770		80 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 170 Watts (213%)

Memory Bandwidth

In theory, the Radeon HD 4850 X2 1GB should be 77% faster than the Radeon HD 7770 overall, because of its greater bandwidth. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 55104 (77%)

Texel Rate

The Radeon HD 4850 X2 1GB will be quite a bit (more or less 25%) faster with regards to anisotropic filtering than the Radeon HD 7770. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 7770		40000 Mtexels/sec
	Difference: 10000 (25%)

Pixel Rate

The Radeon HD 4850 X2 1GB should be much (about 25%) more effective at AA than the Radeon HD 7770, and should be able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 7770		16000 Mpixels/sec
	Difference: 4000 (25%)

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: Bandwidth is the max amount of data (counted in megabytes per second) that can be transferred over the external memory interface in one second. It's calculated by multiplying the card's bus width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card could possibly record to the 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 - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.