Radeon HD 6770 1GB vs Radeon HD 7770

Intro

Compare those specifications to the Radeon HD 7770, which uses a 28 nm design. AMD has set the core frequency at 1000 MHz. The GDDR5 RAM runs at a frequency of 1125 MHz on this particular card. It features 640 SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770		80 Watts
Radeon HD 6770 1GB		108 Watts
	Difference: 28 Watts (35%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7770 will be 7% faster than the Radeon HD 6770 1GB in general, due to its greater data rate. (explain)

Radeon HD 7770		72000 MB/sec
Radeon HD 6770 1GB		67200 MB/sec
	Difference: 4800 (7%)

Texel Rate

The Radeon HD 7770 should be a little bit (more or less 11%) better at AF than the Radeon HD 6770 1GB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 6770 1GB		36000 Mtexels/sec
	Difference: 4000 (11%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 7770 is superior to the Radeon HD 6770 1GB, not by a very large margin though. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 6770 1GB		14400 Mpixels/sec
	Difference: 1600 (11%)

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 information (measured in MB per second) that can be transferred across the external memory interface in one second. It is calculated by multiplying the card's bus width by its memory speed. If it uses DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, 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 applied per second. This is calculated by multiplying the total number of texture units by the core clock speed of the chip. The better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.