GeForce GT 640 DDR3 vs Radeon HD 4650 1GB

Intro

Compare those specifications to the Radeon HD 4650 1GB, which comes with a core clock frequency of 600 MHz and a GDDR3 memory speed of 700 MHz. It also makes use of a 128-bit memory bus, and makes use of a 55 nm design. It is made up of 320(64x5) SPUs, 32 Texture Address Units, and 8 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4650 1GB		55 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 10 Watts (18%)

Memory Bandwidth

The GeForce GT 640 DDR3 should theoretically perform quite a bit faster than the Radeon HD 4650 1GB overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
Radeon HD 4650 1GB		22400 MB/sec
	Difference: 34624 (155%)

Texel Rate

The GeForce GT 640 DDR3 will be much (about 50%) faster with regards to anisotropic filtering than the Radeon HD 4650 1GB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 4650 1GB		19200 Mtexels/sec
	Difference: 9600 (50%)

Pixel Rate

The GeForce GT 640 DDR3 will be a lot (more or less 200%) more effective at anti-aliasing than the Radeon HD 4650 1GB, and also should be capable of handling higher resolutions without losing too much performance. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 4650 1GB		4800 Mpixels/sec
	Difference: 9600 (200%)

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 maximum amount of information (counted in megabytes per second) that can be transported past the external memory interface within a second. It's calculated by multiplying the card's bus width by its memory speed. In the case of DDR memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be processed in one second. This figure is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better this number, the better the video 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 that the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs 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 lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to reach the max fill rate.