GeForce 8800 Ultra vs GeForce GT 640 DDR3

Intro

Compare those specifications to the GeForce GT 640 DDR3, which makes use of a 28 nm design. nVidia has set the core frequency at 900 MHz. The DDR3 RAM runs at a frequency of 1782 MHz on this particular model. It features 384 SPUs as well as 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 8800 Ultra		171 Watts
	Difference: 106 Watts (163%)

Memory Bandwidth

Theoretically speaking, the GeForce 8800 Ultra should be quite a bit faster than the GeForce GT 640 DDR3 in general. (explain)

GeForce 8800 Ultra		103680 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 46656 (82%)

Texel Rate

The GeForce 8800 Ultra will be a lot (more or less 36%) better at AF than the GeForce GT 640 DDR3. (explain)

GeForce 8800 Ultra		39168 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 10368 (36%)

Pixel Rate

The GeForce 8800 Ultra should be a bit (more or less 2%) faster with regards to anti-aliasing than the GeForce GT 640 DDR3, and also will be capable of handling higher resolutions without losing too much performance. (explain)

GeForce 8800 Ultra		14688 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 288 (2%)

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 (in units of megabytes per second) that can be transported past the external memory interface within a second. It's calculated by multiplying the interface width by the speed of its memory. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to its local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called 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 bandwidth is, the lower the potential to get to the maximum fill rate.