Radeon HD 4870 2GB vs Radeon HD 6770 1GB

Intro

Compare all that to the Radeon HD 6770 1GB, which has a clock speed of 900 MHz and a GDDR5 memory frequency of 1050 MHz. It also uses a 128-bit bus, and uses 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 1GB		108 Watts
Radeon HD 4870 2GB		150 Watts
	Difference: 42 Watts (39%)

Memory Bandwidth

As far as performance goes, the Radeon HD 4870 2GB should in theory be much superior to the Radeon HD 6770 1GB in general. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon HD 6770 1GB		67200 MB/sec
	Difference: 48000 (71%)

Texel Rate

The Radeon HD 6770 1GB will be a bit (approximately 20%) better at anisotropic filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 6770 1GB		36000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 6000 (20%)

Pixel Rate

The Radeon HD 6770 1GB will be a little bit (approximately 20%) more effective at full screen anti-aliasing than the Radeon HD 4870 2GB, and able to handle higher resolutions while still performing well. (explain)

Radeon HD 6770 1GB		14400 Mpixels/sec
Radeon HD 4870 2GB		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: Bandwidth is the largest amount of data (measured in MB per second) that can be transported over the external memory interface in a second. The number is worked out by multiplying the bus width by its memory speed. If the card has DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better 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 are applied per second. This is worked out by multiplying the total number of texture units by the core clock speed of the chip. The better this number, the better the graphics card will be at handling 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 can possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called 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, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.