GeForce GT 640 DDR3 vs GeForce GTS 450 1GB

Intro

Compare those specifications to the GeForce GTS 450 1GB, which features GPU clock speed of 783 MHz, and 1024 MB of GDDR5 RAM running at 902 MHz through a 128-bit bus. It also is comprised of 192 Stream Processors, 32 TAUs, and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GTS 450 1GB		106 Watts
	Difference: 41 Watts (63%)

Memory Bandwidth

Theoretically speaking, the GeForce GTS 450 1GB should be 1% quicker than the GeForce GT 640 DDR3 overall, because of its greater data rate. (explain)

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

Texel Rate

The GeForce GT 640 DDR3 is a little bit (approximately 15%) faster with regards to texture filtering than the GeForce GTS 450 1GB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GTS 450 1GB		25056 Mtexels/sec
	Difference: 3744 (15%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the GeForce GT 640 DDR3 is a better choice, not by a very large margin though. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce GTS 450 1GB		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: Memory bandwidth is the max amount of data (counted in megabytes per second) that can be transported over the external memory interface within a second. The number is worked out by multiplying the bus width by its memory speed. In the case of DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher 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 amount of texture map elements (texels) that are processed per second. This is worked out by multiplying the total number of texture units by the core clock 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 applied in one second.

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