GeForce GT 640 DDR3 vs Geforce GTX 770

Intro

Compare those specs to the Geforce GTX 770, which features a core clock frequency of 1046 MHz and a GDDR5 memory speed of 1753 MHz. It also features a 256-bit memory bus, and uses a 28 nm design. It is comprised of 1536 SPUs, 128 TAUs, and 32 Raster Operation 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 770		7854 points
GeForce GT 640 DDR3		1560 points
	Difference: 6294 (403%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Geforce GTX 770		230 Watts
	Difference: 165 Watts (254%)

Memory Bandwidth

Theoretically speaking, the Geforce GTX 770 should be quite a bit faster than the GeForce GT 640 DDR3 overall. (explain)

Geforce GTX 770		224384 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 167360 (293%)

Texel Rate

The Geforce GTX 770 will be much (more or less 365%) more effective at texture filtering than the GeForce GT 640 DDR3. (explain)

Geforce GTX 770		133888 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 105088 (365%)

Pixel Rate

The Geforce GTX 770 should be a lot (approximately 132%) better at full screen anti-aliasing than the GeForce GT 640 DDR3, and also should be able to handle higher resolutions more effectively. (explain)

Geforce GTX 770		33472 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 19072 (132%)

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 largest amount of information (in units of megabytes per second) that can be transferred across the external memory interface in a second. It is worked out by multiplying the bus width by its memory speed. In the case of DDR memory, it must be multiplied by 2 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 anti-aliasing, High Dynamic Range and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics card could possibly write to its local memory per second - measured in millions of pixels per second. The number is worked out by multiplying the amount of colour ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate also depends on lots of other factors, most notably the memory bandwidth - the lower the memory bandwidth is, the lower the potential to reach the max fill rate.