GeForce GT 640 DDR3 vs Radeon HD 4730

Intro

Compare those specs to the Radeon HD 4730, which has a core clock speed of 700 MHz and a GDDR5 memory frequency of 900 MHz. It also features a 128-bit bus, and uses a 55 nm design. It features 640(128x5) SPUs, 32 Texture Address Units, and 8 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 4730		140 Watts
	Difference: 75 Watts (115%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4730 is 1% quicker than the GeForce GT 640 DDR3 overall, because of its greater bandwidth. (explain)

Radeon HD 4730		57600 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 576 (1%)

Texel Rate

The GeForce GT 640 DDR3 will be much (about 29%) better at texture filtering than the Radeon HD 4730. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 4730		22400 Mtexels/sec
	Difference: 6400 (29%)

Pixel Rate

The GeForce GT 640 DDR3 will be much (approximately 157%) faster with regards to anti-aliasing than the Radeon HD 4730, and also will be able to handle higher screen resolutions more effectively. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 4730		5600 Mpixels/sec
	Difference: 8800 (157%)

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 (in units of megabytes per second) that can be transferred across the external memory interface within a second. It is calculated by multiplying the bus width by the speed of its memory. If the card has DDR type RAM, it should be multiplied by 2 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 high resolutions.

Texel Rate: Texel rate is the maximum amount of texture map elements (texels) that are applied per second. This is worked out by multiplying the total texture units of the card by the core speed of the chip. The higher this number, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels 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 number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.