Radeon HD 4770 vs Radeon HD 7770

Intro

Compare all of 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 runs at a frequency of 1125 MHz on this particular model. It features 640 SPUs as well as 40 TAUs and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Both cards have the same power consumption.

Memory Bandwidth

The Radeon HD 7770, in theory, should be much faster than the Radeon HD 4770 overall. (explain)

Radeon HD 7770		72000 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 20800 (41%)

Texel Rate

The Radeon HD 7770 is quite a bit (approximately 67%) more effective at anisotropic filtering than the Radeon HD 4770. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 16000 (67%)

Pixel Rate

The Radeon HD 7770 should be quite a bit (about 33%) more effective at full screen anti-aliasing than the Radeon HD 4770, and will be capable of handling higher resolutions without losing too much performance. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4770		12000 Mpixels/sec
	Difference: 4000 (33%)

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 MB per second) that can be transferred over the external memory interface in a second. It is calculated by multiplying the card's bus width by the speed of its memory. In the case of DDR RAM, the result should be multiplied by 2 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, HDR and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This number is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the video 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 could possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.