Radeon HD 4850 X2 1GB vs Radeon HD 6770

Intro

Compare those specifications to the Radeon HD 6770, which has a core clock speed of 900 MHz and a GDDR5 memory frequency of 1050 MHz. It also features a 128-bit bus, and uses a 40 nm design. It is made up of 800 SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6770		108 Watts
Radeon HD 4850 X2 1GB		250 Watts
	Difference: 142 Watts (131%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4850 X2 1GB should perform much faster than the Radeon HD 6770 in general. (explain)

Radeon HD 4850 X2 1GB		127104 MB/sec
Radeon HD 6770		67200 MB/sec
	Difference: 59904 (89%)

Texel Rate

The Radeon HD 4850 X2 1GB is much (approximately 39%) faster with regards to anisotropic filtering than the Radeon HD 6770. (explain)

Radeon HD 4850 X2 1GB		50000 Mtexels/sec
Radeon HD 6770		36000 Mtexels/sec
	Difference: 14000 (39%)

Pixel Rate

The Radeon HD 4850 X2 1GB will be quite a bit (about 39%) faster with regards to AA than the Radeon HD 6770, and also should be capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 4850 X2 1GB		20000 Mpixels/sec
Radeon HD 6770		14400 Mpixels/sec
	Difference: 5600 (39%)

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 information (counted in MB per second) that can be transferred across the external memory interface in one second. The number is worked out by multiplying the card's interface width by its memory speed. In the case of DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied per second. This figure is worked out by multiplying the total number of texture units 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 in a second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to 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 maximum fill rate.