GeForce GT 220 GDDR3 vs GeForce GT 640 DDR3

Intro

Compare those specifications to the GeForce GT 640 DDR3, which has 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 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 220 GDDR3		58 Watts
GeForce GT 640 DDR3		65 Watts
	Difference: 7 Watts (12%)

Memory Bandwidth

Performance-wise, the GeForce GT 640 DDR3 should in theory be a lot better than the GeForce GT 220 GDDR3 in general. (explain)

GeForce GT 640 DDR3		57024 MB/sec
GeForce GT 220 GDDR3		32384 MB/sec
	Difference: 24640 (76%)

Texel Rate

The GeForce GT 640 DDR3 will be a lot (more or less 188%) better at AF than the GeForce GT 220 GDDR3. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
GeForce GT 220 GDDR3		10000 Mtexels/sec
	Difference: 18800 (188%)

Pixel Rate

The GeForce GT 640 DDR3 will be much (approximately 188%) better at anti-aliasing than the GeForce GT 220 GDDR3, and will be able to handle higher screen resolutions while still performing well. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
GeForce GT 220 GDDR3		5000 Mpixels/sec
	Difference: 9400 (188%)

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 data (counted in MB per second) that can be moved past the external memory interface within a second. It's worked out by multiplying the bus width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, 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 processed in one second. This figure is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed in one second.

Pixel Rate: Pixel rate is the maximum number of pixels the graphics card can possibly write to the local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the amount of ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.