GeForce GT 640 DDR3 vs Radeon HD 3870 1GB

Intro

Compare that to the Radeon HD 3870 1GB, which makes use of a 55 nm design. AMD has clocked the core frequency at 775 MHz. The GDDR4 RAM works at a frequency of 1125 MHz on this specific model. It features 320(64x5) SPUs as well as 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

Theoretically, the Radeon HD 3870 1GB should perform quite a bit faster than the GeForce GT 640 DDR3 in general. (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 quite a bit (approximately 132%) faster with regards to texture filtering 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

If using a high screen resolution is important to you, then the GeForce GT 640 DDR3 is the winner, though not by far. (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: Bandwidth is the largest amount of data (counted in MB per second) that can be moved across the external memory interface in a second. It is worked out by multiplying the card's bus width by the speed of its memory. If the card has DDR memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum 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 clock speed of the chip. The better the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in one second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka 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 bandwidth is, the lower the potential to get to the maximum fill rate.