Radeon HD 4850 512MB vs Radeon HD 6770

Intro

Compare those specs to the Radeon HD 6770, which comes with a core clock speed of 900 MHz and a GDDR5 memory frequency of 1050 MHz. It also uses a 128-bit memory bus, and makes use of a 40 nm design. It is comprised of 800 SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6770		108 Watts
Radeon HD 4850 512MB		110 Watts
	Difference: 2 Watts (2%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6770 will be 6% faster than the Radeon HD 4850 512MB overall, due to its greater data rate. (explain)

Radeon HD 6770		67200 MB/sec
Radeon HD 4850 512MB		63552 MB/sec
	Difference: 3648 (6%)

Texel Rate

The Radeon HD 6770 is quite a bit (more or less 44%) better at AF than the Radeon HD 4850 512MB. (explain)

Radeon HD 6770		36000 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 11000 (44%)

Pixel Rate

The Radeon HD 6770 will be a lot (about 44%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 512MB, and also capable of handling higher resolutions more effectively. (explain)

Radeon HD 6770		14400 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 4400 (44%)

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.

Price Comparison

Specifications

Memory Bandwidth: Bandwidth is the largest amount of information (measured in MB per second) that can be moved over the external memory interface within a second. The number is calculated by multiplying the card's interface width by its memory speed. In the case of DDR type memory, the result should be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster 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 number of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the graphics 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 card can possibly write to the local memory in one second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.