GeForce GT 640 DDR3 vs GeForce GTX 980

Intro

Compare those specifications to the GeForce GTX 980, which features core clock speeds of 1126 MHz on the GPU, and 1750 MHz on the 4096 MB of GDDR5 memory. It features 2048 SPUs along with 128 Texture Address Units and 64 Rasterization Operator Units.

Display Graphs

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Benchmarks

These are real-world performance benchmarks that were submitted by Hardware Compare users. The scores seen here are the average of all benchmarks submitted for each respective test and hardware.

3DMark Fire Strike Graphics Score

GeForce GTX 980		13552 points
GeForce GT 640 DDR3		1560 points
	Difference: 11992 (769%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
GeForce GTX 980		165 Watts
	Difference: 100 Watts (154%)

Memory Bandwidth

Theoretically speaking, the GeForce GTX 980 will be 293% quicker than the GeForce GT 640 DDR3 in general, due to its greater data rate. (explain)

GeForce GTX 980		224000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 166976 (293%)

Texel Rate

The GeForce GTX 980 is quite a bit (about 400%) better at texture filtering than the GeForce GT 640 DDR3. (explain)

GeForce GTX 980		144128 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 115328 (400%)

Pixel Rate

The GeForce GTX 980 will be a lot (approximately 400%) faster with regards to full screen anti-aliasing than the GeForce GT 640 DDR3, and also will be able to handle higher screen resolutions without losing too much performance. (explain)

GeForce GTX 980		72064 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 57664 (400%)

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 largest amount of data (measured in MB per second) that can be transferred across the external memory interface within a second. The number is worked out by multiplying the card's bus width by its memory clock speed. If it uses DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly record to its local memory in one second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to reach the maximum fill rate.