Radeon HD 4770 vs Radeon HD 6770 1GB

Intro

Compare all of that to the Radeon HD 6770 1GB, which makes use of a 40 nm design. AMD has clocked the core speed at 900 MHz. The GDDR5 memory is set to run at a frequency of 1050 MHz on this particular card. It features 800 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 4770		80 Watts
Radeon HD 6770 1GB		108 Watts
	Difference: 28 Watts (35%)

Memory Bandwidth

In theory, the Radeon HD 6770 1GB should be 31% faster than the Radeon HD 4770 in general, due to its greater data rate. (explain)

Radeon HD 6770 1GB		67200 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 16000 (31%)

Texel Rate

The Radeon HD 6770 1GB should be a lot (about 50%) more effective at anisotropic filtering than the Radeon HD 4770. (explain)

Radeon HD 6770 1GB		36000 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 12000 (50%)

Pixel Rate

The Radeon HD 6770 1GB is a little bit (approximately 20%) faster with regards to anti-aliasing than the Radeon HD 4770, and able to handle higher resolutions while still performing well. (explain)

Radeon HD 6770 1GB		14400 Mpixels/sec
Radeon HD 4770		12000 Mpixels/sec
	Difference: 2400 (20%)

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 largest amount of information (measured in megabytes per second) that can be transferred past the external memory interface in one second. It is calculated by multiplying the bus width by its memory clock speed. In the case of DDR type memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be applied in one second. This number is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the most pixels the video card could possibly write to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate also depends on many 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.