Radeon HD 4650 512MB vs Radeon HD 7770

Intro

Compare all of that to the Radeon HD 7770, which features clock speeds of 1000 MHz on the GPU, and 1125 MHz on the 1024 MB of GDDR5 memory. It features 640 SPUs along with 40 Texture Address Units and 16 ROPs.

Display Graphs

Hide Graphs

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

In theory, the Radeon HD 7770 should be 350% faster than the Radeon HD 4650 512MB in general, due to its higher bandwidth. (explain)

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

Texel Rate

The Radeon HD 7770 will be quite a bit (about 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 running with a high screen resolution is important to you, then the Radeon HD 7770 is the winner, by far. (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: Memory bandwidth is the largest amount of data (measured in MB per second) that can be transported past the external memory interface in a second. The number is worked out by multiplying the bus width by its memory clock speed. If it uses DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. 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 amount of texture map elements (texels) that can be processed in one second. This is calculated 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 texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Raster Operations Pipelines by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.