GeForce GT 640 DDR3 vs GeForce GTS 250 1GB

Intro

Compare those specs to the GeForce GTS 250 1GB, which has a clock frequency of 738 MHz and a GDDR3 memory frequency of 1100 MHz. It also makes use of a 256-bit bus, and uses a 65/55 nm design. It is comprised of 128 SPUs, 64 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GTS 250 1GB		145 Watts
	Difference: 80 Watts (123%)

Memory Bandwidth

As far as performance goes, the GeForce GTS 250 1GB should in theory be a lot better than the GeForce GT 640 DDR3 overall. (explain)

GeForce GTS 250 1GB		70400 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 13376 (23%)

Texel Rate

The GeForce GTS 250 1GB will be a lot (approximately 64%) more effective at anisotropic filtering than the GeForce GT 640 DDR3. (explain)

GeForce GTS 250 1GB		47232 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 18432 (64%)

Pixel Rate

If running with a high resolution is important to you, then the GeForce GT 640 DDR3 is the winner, by far. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce GTS 250 1GB		11808 Mpixels/sec
	Difference: 2592 (22%)

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 largest amount of information (counted in megabytes per second) that can be transported past the external memory interface within a second. It is calculated by multiplying the interface width by its memory clock speed. If it uses DDR memory, the result should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster 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 amount of texture map elements (texels) that are processed per second. This is worked out by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Render Output Units by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.