GeForce GT 640 DDR3 vs GeForce GTS 250 1GB

Intro

Compare all of that to the GeForce GTS 250 1GB, which features a core clock frequency of 738 MHz and a GDDR3 memory frequency of 1100 MHz. It also makes use of a 256-bit memory bus, and makes use of a 65/55 nm design. It is made up of 128 SPUs, 64 TAUs, 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 should be much (approximately 64%) faster with regards to 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 a large margin. (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 maximum amount of data (in units of megabytes per second) that can be moved across the external memory interface in a second. The number is calculated by multiplying the interface width by its memory clock speed. If the card has DDR RAM, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - aka 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, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the max fill rate.