Radeon HD 4650 512MB vs Radeon HD 7770

Intro

Compare that to the Radeon HD 7770, which features GPU core speed of 1000 MHz, and 1024 MB of GDDR5 memory running at 1125 MHz through a 128-bit bus. It also features 640 Stream Processors, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 512MB		55 Watts
Radeon HD 7770		80 Watts
	Difference: 25 Watts (45%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7770 will be 350% faster than the Radeon HD 4650 512MB in general, because of its greater bandwidth. (explain)

Radeon HD 7770		72000 MB/sec
Radeon HD 4650 512MB		16000 MB/sec
	Difference: 56000 (350%)

Texel Rate

The Radeon HD 7770 is quite a bit (more or less 108%) faster with regards to anisotropic filtering than the Radeon HD 4650 512MB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4650 512MB		19200 Mtexels/sec
	Difference: 20800 (108%)

Pixel Rate

If using a high resolution is important to you, then the Radeon HD 7770 is the winner, by a large margin. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4650 512MB		4800 Mpixels/sec
	Difference: 11200 (233%)

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 maximum amount of data (in units of megabytes per second) that can be transported past the external memory interface within a second. It is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR type RAM, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, 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 are applied per second. This number is worked out by multiplying the total amount of texture units of the card by the core 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 in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics card can possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.