GeForce GT 640 DDR3 vs Radeon HD 5770

Intro

Compare those specs to the Radeon HD 5770, which comes with GPU clock speed of 850 MHz, and 1024 MB of GDDR5 RAM set to run at 1200 MHz through a 128-bit bus. It also features 800(160x5) Stream Processors, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 5770		108 Watts
	Difference: 43 Watts (66%)

Memory Bandwidth

As far as performance goes, the Radeon HD 5770 should theoretically be a lot superior to the GeForce GT 640 DDR3 in general. (explain)

Radeon HD 5770		76800 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 19776 (35%)

Texel Rate

The Radeon HD 5770 will be a little bit (more or less 18%) better at anisotropic filtering than the GeForce GT 640 DDR3. (explain)

Radeon HD 5770		34000 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 5200 (18%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the GeForce GT 640 DDR3 is superior to the Radeon HD 5770, but it probably won't make a huge difference. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 5770		13600 Mpixels/sec
	Difference: 800 (6%)

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 data (in units of MB per second) that can be moved past the external memory interface in one second. It's worked out by multiplying the card's bus width by its memory clock speed. In the case of DDR memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that can be processed in one second. This number is worked out by multiplying the total number of texture units 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 processed in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly record to the local memory per 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 rate also depends on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.