Radeon HD 6770 1GB vs Radeon HD 7770

Intro

Compare all that to the Radeon HD 7770, which makes use of a 28 nm design. AMD has set the core speed at 1000 MHz. The GDDR5 RAM works at a speed of 1125 MHz on this particular model. It features 640 SPUs along with 40 TAUs 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 should be 7% quicker than the Radeon HD 6770 1GB overall, because of its greater bandwidth. (explain)

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

Texel Rate

The Radeon HD 7770 will be a bit (more or less 11%) faster with regards to 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

The Radeon HD 7770 should be a small bit (about 11%) more effective at FSAA than the Radeon HD 6770 1GB, and able to handle higher resolutions while still performing well. (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 max amount of information (in units of MB per second) that can be moved across the external memory interface in a second. The number is worked out by multiplying the card's bus width by its memory speed. In the case of DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed in one second. This figure is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better this number, the better the 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 maximum number of pixels the video card could possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on many other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to get to the maximum fill rate.