GeForce GT 640 DDR3 vs Radeon HD 7850

Intro

Compare those specs to the Radeon HD 7850, which has GPU core speed of 860 MHz, and 2048 MB of GDDR5 memory set to run at 1200 MHz through a 256-bit bus. It also is made up of 1024 SPUs, 64 Texture Address Units, and 32 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

Radeon HD 7850		5200 points
GeForce GT 640 DDR3		1560 points
	Difference: 3640 (233%)

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 7850		130 Watts
	Difference: 65 Watts (100%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 7850 should be 169% faster than the GeForce GT 640 DDR3 overall, due to its higher bandwidth. (explain)

Radeon HD 7850		153600 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 96576 (169%)

Texel Rate

The Radeon HD 7850 will be quite a bit (more or less 91%) better at AF than the GeForce GT 640 DDR3. (explain)

Radeon HD 7850		55040 Mtexels/sec
GeForce GT 640 DDR3		28800 Mtexels/sec
	Difference: 26240 (91%)

Pixel Rate

The Radeon HD 7850 should be much (about 91%) better at anti-aliasing than the GeForce GT 640 DDR3, and will be able to handle higher resolutions better. (explain)

Radeon HD 7850		27520 Mpixels/sec
GeForce GT 640 DDR3		14400 Mpixels/sec
	Difference: 13120 (91%)

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 max amount of information (measured in MB per second) that can be transported across the external memory interface in a second. The number is calculated by multiplying the card's interface width by its memory speed. In the case of DDR type memory, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The better the bandwidth is, the faster 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 amount of texture map elements (texels) that are applied per second. This number is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The better this number, the better the graphics card will be at 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 write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the number of ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.