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GeForce GT 640 DDR3 vs Radeon HD 4830 512MB

Intro

The GeForce GT 640 DDR3 features core speeds of 900 MHz on the GPU, and 1782 MHz on the 2048 MB of DDR3 memory. It features 384 SPUs along with 32 TAUs and 16 Rasterization Operator Units.

Compare those specs to the Radeon HD 4830 512MB, which uses a 55 nm design. AMD has clocked the core speed at 575 MHz. The GDDR3 RAM works at a speed of 900 MHz on this particular card. It features 640(128x5) SPUs as well as 32 Texture Address Units and 16 ROPs.

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 4830 512MB		95 Watts
	Difference: 30 Watts (46%)

Memory Bandwidth

Performance-wise, the Radeon HD 4830 512MB should theoretically be just a bit superior to the GeForce GT 640 DDR3 overall. (explain)

Radeon HD 4830 512MB		57600 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 576 (1%)

Texel Rate

The GeForce GT 640 DDR3 will be a lot (approximately 57%) better at anisotropic filtering than the Radeon HD 4830 512MB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 4830 512MB		18400 Mtexels/sec
	Difference: 10400 (57%)

Pixel Rate

If running with a high resolution is important to you, then the GeForce GT 640 DDR3 is superior to the Radeon HD 4830 512MB, by far. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 4830 512MB		9200 Mpixels/sec
	Difference: 5200 (57%)

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

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GeForce GT 640 DDR3

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Radeon HD 4830 512MB

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Specifications

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Model	GeForce GT 640 DDR3	Radeon HD 4830 512MB
Manufacturer	nVidia	AMD
Year	June 2012	Oct 21, 2008
Code Name	GK107	RV770 LE
Memory	2048 MB	512 MB
Core Speed	900 MHz	575 MHz
Memory Speed	3564 MHz	1800 MHz
Power (Max TDP)	65 watts	95 watts
Bandwidth	57024 MB/sec	57600 MB/sec
Texel Rate	28800 Mtexels/sec	18400 Mtexels/sec
Pixel Rate	14400 Mpixels/sec	9200 Mpixels/sec
Unified Shaders	384	640(128x5)
Texture Mapping Units	32	32
Render Output Units	16	16
Bus Type	DDR3	GDDR3
Bus Width	128-bit	256-bit
Fab Process	28 nm	55 nm
Transistors	1300 million	956 million
Bus	PCIe 3.0 x16	PCIe 2.0 x16
DirectX Version	DirectX 11.0	DirectX 10.1
OpenGL Version	OpenGL 4.2	OpenGL 3.0

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

Texel Rate: Texel rate is the maximum texture map elements (texels) that can be applied per second. This figure is worked out by multiplying the total amount 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Raster Operations Pipelines by the the card's 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 output rate also depends on many other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the potential to get to the max fill rate.

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