Radeon HD 4850 1GB vs Radeon HD 6770

Intro

Compare that to the Radeon HD 6770, which features a clock speed of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also makes use of a 128-bit bus, and uses 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 1GB		110 Watts
	Difference: 2 Watts (2%)

Memory Bandwidth

In theory, the Radeon HD 6770 will be 6% faster than the Radeon HD 4850 1GB in general, because of its higher data rate. (explain)

Radeon HD 6770		67200 MB/sec
Radeon HD 4850 1GB		63552 MB/sec
	Difference: 3648 (6%)

Texel Rate

The Radeon HD 6770 should be quite a bit (about 44%) more effective at texture filtering than the Radeon HD 4850 1GB. (explain)

Radeon HD 6770		36000 Mtexels/sec
Radeon HD 4850 1GB		25000 Mtexels/sec
	Difference: 11000 (44%)

Pixel Rate

The Radeon HD 6770 will be much (about 44%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 1GB, and also will be capable of handling higher screen resolutions better. (explain)

Radeon HD 6770		14400 Mpixels/sec
Radeon HD 4850 1GB		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: Memory bandwidth is the maximum amount of data (in units of megabytes per second) that can be transferred across the external memory interface within a second. It's calculated by multiplying the interface width by the speed of its memory. In the case of DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better 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 number of texture map elements (texels) that are applied in one second. This number is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better this number, the better the video card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.