GeForce GT 640 DDR3 vs GeForce GTX 465

Intro

Compare those specifications to the GeForce GTX 465, which features a core clock frequency of 607 MHz and a GDDR5 memory frequency of 802 MHz. It also makes use of a 256-bit bus, and uses a 40 nm design. It is made up of 352 SPUs, 44 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GTX 465		200 Watts
	Difference: 135 Watts (208%)

Memory Bandwidth

In theory, the GeForce GTX 465 should perform quite a bit faster than the GeForce GT 640 DDR3 in general. (explain)

GeForce GTX 465		102592 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 45568 (80%)

Texel Rate

The GeForce GT 640 DDR3 is a little bit (about 8%) more effective at AF than the GeForce GTX 465. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GTX 465		26708 Mtexels/sec
	Difference: 2092 (8%)

Pixel Rate

The GeForce GTX 465 should be a lot (approximately 35%) more effective at anti-aliasing than the GeForce GT 640 DDR3, and should be able to handle higher resolutions while still performing well. (explain)

GeForce GTX 465		19424 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 5024 (35%)

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 information (in units of MB per second) that can be transferred across the external memory interface in a second. The number is calculated by multiplying the card's bus width by the speed of its memory. If it uses DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better 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 are applied per second. This number is worked out by multiplying the total amount of texture units by the core speed of the chip. The better this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly write to the local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output 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 get to the maximum fill rate.