GeForce 9800 GTX+ vs GeForce GT 640 DDR3

Intro

Compare that to the GeForce GT 640 DDR3, which comes with GPU core speed of 900 MHz, and 2048 MB of DDR3 RAM running at 1782 MHz through a 128-bit bus. It also is comprised of 384 SPUs, 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 9800 GTX+		145 Watts
	Difference: 80 Watts (123%)

Memory Bandwidth

Theoretically, the GeForce 9800 GTX+ should be quite a bit faster than the GeForce GT 640 DDR3 in general. (explain)

GeForce 9800 GTX+		70400 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 13376 (23%)

Texel Rate

The GeForce 9800 GTX+ is a lot (about 64%) better at anisotropic filtering than the GeForce GT 640 DDR3. (explain)

GeForce 9800 GTX+		47232 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 18432 (64%)

Pixel Rate

If using a high screen resolution is important to you, then the GeForce GT 640 DDR3 is superior to the GeForce 9800 GTX+, and very much so. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 9800 GTX+		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: Memory bandwidth is the largest amount of data (in units of MB per second) that can be moved across the external memory interface in a second. It is worked out by multiplying the interface width by the speed of its memory. If it uses DDR RAM, the result should be multiplied by 2 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 anti-aliasing, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This is worked out by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the graphics 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 can possibly write to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.