GeForce GT 640 DDR3 vs Radeon HD 6770

Intro

Compare those specs to the Radeon HD 6770, which makes use of a 40 nm design. AMD has clocked the core frequency at 900 MHz. The GDDR5 memory works at a frequency of 1050 MHz on this particular card. It features 800 SPUs along with 40 TAUs and 16 ROPs.

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 GT 640 DDR3		1560 points
Radeon HD 6770		1520 points
	Difference: 40 (3%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 6770		108 Watts
	Difference: 43 Watts (66%)

Memory Bandwidth

Performance-wise, the Radeon HD 6770 should in theory be a bit superior to the GeForce GT 640 DDR3 in general. (explain)

Radeon HD 6770		67200 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 10176 (18%)

Texel Rate

The Radeon HD 6770 is quite a bit (more or less 25%) better at AF than the GeForce GT 640 DDR3. (explain)

Radeon HD 6770		36000 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 7200 (25%)

Pixel Rate

Both cards have the exact same pixel fill rate, so theoretically they should perform equally good at at AA, and be able to handle the same screen resolutions. (explain)

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 maximum amount of data (in units of megabytes per second) that can be moved over the external memory interface within a second. The number is worked out by multiplying the bus width by its memory speed. If it uses DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per second. This figure is worked out by multiplying the total amount of texture units 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 most pixels that the graphics card can possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate is also dependant on lots of other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.