Radeon HD 4850 2GB vs Radeon HD 6770 1GB

Intro

Compare those specs to the Radeon HD 6770 1GB, which features core speeds of 900 MHz on the GPU, and 1050 MHz on the 1024 MB of GDDR5 RAM. It features 800 SPUs as well as 40 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 6770 1GB		108 Watts
Radeon HD 4850 2GB		110 Watts
	Difference: 2 Watts (2%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 6770 1GB should be 6% faster than the Radeon HD 4850 2GB overall, due to its higher bandwidth. (explain)

Radeon HD 6770 1GB		67200 MB/sec
Radeon HD 4850 2GB		63552 MB/sec
	Difference: 3648 (6%)

Texel Rate

The Radeon HD 6770 1GB will be quite a bit (about 44%) better at texture filtering than the Radeon HD 4850 2GB. (explain)

Radeon HD 6770 1GB		36000 Mtexels/sec
Radeon HD 4850 2GB		25000 Mtexels/sec
	Difference: 11000 (44%)

Pixel Rate

The Radeon HD 6770 1GB will be a lot (more or less 44%) better at AA than the Radeon HD 4850 2GB, and able to handle higher resolutions more effectively. (explain)

Radeon HD 6770 1GB		14400 Mpixels/sec
Radeon HD 4850 2GB		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 max amount of information (in units of MB per second) that can be transferred over the external memory interface in one second. The number is calculated by multiplying the interface width by its memory clock speed. In the case of DDR type RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed per second. This is worked out by multiplying the total 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 applied in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Render Output Units by the the core clock speed. 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 lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the max fill rate.