GeForce GT 640 DDR3 vs GeForce GTS 450

Intro

Compare those specs to the GeForce GTS 450, which has a clock frequency of 783 MHz and a GDDR5 memory speed of 902 MHz. It also features a 128-bit bus, and uses a 40 nm design. It is made up of 192 SPUs, 32 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Benchmarks

These are real-world performance benchmarks that were submitted by Hardware Compare users. The scores seen here are the average of all benchmarks submitted for each respective test and hardware.

3DMark Fire Strike Graphics Score

GeForce GT 640 DDR3		1560 points
GeForce GTS 450		1453 points
	Difference: 107 (7%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GTS 450		106 Watts
	Difference: 41 Watts (63%)

Memory Bandwidth

Theoretically speaking, the GeForce GTS 450 will be 1% quicker than the GeForce GT 640 DDR3 in general, because of its greater bandwidth. (explain)

GeForce GTS 450		57728 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 704 (1%)

Texel Rate

The GeForce GT 640 DDR3 is a bit (approximately 15%) better at anisotropic filtering than the GeForce GTS 450. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GTS 450		25056 Mtexels/sec
	Difference: 3744 (15%)

Pixel Rate

The GeForce GT 640 DDR3 will be a small bit (more or less 15%) better at AA than the GeForce GTS 450, and also will be able to handle higher resolutions while still performing well. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce GTS 450		12528 Mpixels/sec
	Difference: 1872 (15%)

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 information (measured in megabytes per second) that can be moved past the external memory interface within a second. It's calculated by multiplying the card's bus width by its memory clock speed. In the case of DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better 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 number of texture map elements (texels) that can be processed per second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.