GeForce GT 640 DDR3 vs Radeon HD 4830 1GB

Intro

Compare those specifications to the Radeon HD 4830 1GB, which uses a 55 nm design. AMD has set the core frequency at 575 MHz. The GDDR4 memory works at a speed of 900 MHz on this specific model. It features 640(128x5) SPUs along with 32 Texture Address Units and 16 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 4830 1GB		95 Watts
	Difference: 30 Watts (46%)

Memory Bandwidth

Performance-wise, the Radeon HD 4830 1GB should in theory be a bit superior to the GeForce GT 640 DDR3 overall. (explain)

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

Texel Rate

The GeForce GT 640 DDR3 should be a lot (approximately 57%) faster with regards to AF than the Radeon HD 4830 1GB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 4830 1GB		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 a better choice, by far. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 4830 1GB		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

Specifications

Memory Bandwidth: Memory bandwidth is the maximum amount of data (in units of megabytes per second) that can be moved over the external memory interface in one second. It is worked out by multiplying the card's bus width by its memory clock speed. If the card has DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The higher the bandwidth is, the better 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 number of texture map elements (texels) that can be applied per second. This figure is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The better this number, 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 most pixels the graphics card could possibly write to the local memory in a second - measured in millions of pixels per second. The number is worked out by multiplying the amount of Raster Operations Pipelines 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 rate is also dependant on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.