GeForce 8600 GT 256MB GDDR3 vs GeForce GT 640 DDR3

Intro

Compare all that to the GeForce GT 640 DDR3, which features a clock speed of 900 MHz and a DDR3 memory speed of 1782 MHz. It also makes use of a 128-bit bus, and uses a 28 nm design. It features 384 SPUs, 32 Texture Address Units, and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce 8600 GT 256MB GDDR3		47 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 18 Watts (38%)

Memory Bandwidth

In theory, the GeForce GT 640 DDR3 should perform quite a bit faster than the GeForce 8600 GT 256MB GDDR3 overall. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce 8600 GT 256MB GDDR3		22400 MB/sec
	Difference: 34624 (155%)

Texel Rate

The GeForce GT 640 DDR3 should be a lot (about 233%) faster with regards to AF than the GeForce 8600 GT 256MB GDDR3. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce 8600 GT 256MB GDDR3		8640 Mtexels/sec
	Difference: 20160 (233%)

Pixel Rate

The GeForce GT 640 DDR3 is a lot (more or less 233%) faster with regards to anti-aliasing than the GeForce 8600 GT 256MB GDDR3, and also should be capable of handling higher resolutions while still performing well. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce 8600 GT 256MB GDDR3		4320 Mpixels/sec
	Difference: 10080 (233%)

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 maximum amount of information (measured in MB per second) that can be moved over the external memory interface in a second. It is calculated by multiplying the interface width by its memory clock speed. If it uses DDR type memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied in one second. This figure is calculated by multiplying the total texture units by the core clock speed of the chip. The higher the texel rate, the better the video 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 that the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.