GeForce GT 640 DDR3 vs GeForce GTX 280

Intro

Compare those specifications to the GeForce GTX 280, which comes with core clock speeds of 602 MHz on the GPU, and 1107 MHz on the 1024 MB of GDDR3 memory. It features 240 SPUs along with 80 TAUs and 32 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GTX 280		236 Watts
	Difference: 171 Watts (263%)

Memory Bandwidth

The GeForce GTX 280 should in theory be quite a bit faster than the GeForce GT 640 DDR3 in general. (explain)

GeForce GTX 280		141696 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 84672 (148%)

Texel Rate

The GeForce GTX 280 is much (approximately 67%) more effective at AF than the GeForce GT 640 DDR3. (explain)

GeForce GTX 280		48160 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 19360 (67%)

Pixel Rate

The GeForce GTX 280 will be much (approximately 34%) faster with regards to AA than the GeForce GT 640 DDR3, and will be able to handle higher screen resolutions while still performing well. (explain)

GeForce GTX 280		19264 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 4864 (34%)

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: Bandwidth is the max amount of information (measured in megabytes per second) that can be transported over the external memory interface in one second. It's calculated by multiplying the interface width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly record to the local memory in a 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 - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.