Radeon HD 4850 1GB vs Radeon HD 6770

Intro

Compare that to the Radeon HD 6770, which has a clock frequency of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also makes use of a 128-bit bus, and makes use of a 40 nm design. It features 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 is 6% quicker than the Radeon HD 4850 1GB in general, due to its higher bandwidth. (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 (approximately 44%) faster with regards to AF 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

If using a high screen resolution is important to you, then the Radeon HD 6770 is a better choice, by far. (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 MB per second) that can be moved across the external memory interface in one second. The number is calculated by multiplying the card's bus width by its memory speed. In the case of DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The higher this number, the better the video 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 that the graphics card can possibly write to the local memory per 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 - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.