GeForce GT 640 DDR3 vs Radeon HD 3870 1GB

Intro

Compare those specs to the Radeon HD 3870 1GB, which comes with a clock frequency of 775 MHz and a GDDR4 memory frequency of 1125 MHz. It also uses a 256-bit memory bus, and makes use of a 55 nm design. It is comprised of 320(64x5) SPUs, 16 TAUs, and 16 ROPs.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 3870 1GB		106 Watts
	Difference: 41 Watts (63%)

Memory Bandwidth

The Radeon HD 3870 1GB should theoretically perform quite a bit faster than the GeForce GT 640 DDR3 overall. (explain)

Radeon HD 3870 1GB		72000 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 14976 (26%)

Texel Rate

The GeForce GT 640 DDR3 should be a lot (about 132%) better at AF than the Radeon HD 3870 1GB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 16400 (132%)

Pixel Rate

The GeForce GT 640 DDR3 will be a bit (approximately 16%) more effective at anti-aliasing than the Radeon HD 3870 1GB, and should be capable of handling higher screen resolutions while still performing well. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 3870 1GB		12400 Mpixels/sec
	Difference: 2000 (16%)

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 maximum amount of information (counted in megabytes per second) that can be moved over the external memory interface within a second. It is worked out by multiplying the card's bus width by its memory speed. If the card has DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The higher the bandwidth is, the better the card will be in general. It especially helps with anti-aliasing, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the most pixels that the graphics chip can possibly record to its local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate also depends on many 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.