GeForce GT 640 DDR3 vs Radeon HD 6770

Intro

Compare all of that to the Radeon HD 6770, which has a clock frequency of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also features a 128-bit memory bus, and uses a 40 nm design. It features 800 SPUs, 40 TAUs, and 16 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 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

As far as performance goes, the Radeon HD 6770 should in theory be a small bit better than the GeForce GT 640 DDR3 overall. (explain)

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

Texel Rate

The Radeon HD 6770 will be a lot (about 25%) better at anisotropic filtering 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 exactly the same pixel rate, so in theory they should perform equally good at at FSAA, and be capable of handling the same 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: Memory bandwidth is the largest amount of information (in units of MB per second) that can be transferred across the external memory interface in one second. The number is calculated by multiplying the bus width by its memory speed. If it uses DDR RAM, it must be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, 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 texture map elements (texels) that can be processed in one second. This number is calculated by multiplying the total 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 applied per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly record to the local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel output rate is also dependant on lots of other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.