GeForce GT 640 DDR3 vs Radeon HD 4850 512MB

Intro

Compare those specifications to the Radeon HD 4850 512MB, which features a core clock frequency of 625 MHz and a GDDR3 memory speed of 993 MHz. It also features a 256-bit memory bus, and makes use of a 55 nm design. It is comprised of 800(160x5) SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

GeForce GT 640 DDR3		65 Watts
Radeon HD 4850 512MB		110 Watts
	Difference: 45 Watts (69%)

Memory Bandwidth

Theoretically, the Radeon HD 4850 512MB should be a little bit faster than the GeForce GT 640 DDR3 overall. (explain)

Radeon HD 4850 512MB		63552 MB/sec
GeForce GT 640 DDR3		57024 MB/sec
	Difference: 6528 (11%)

Texel Rate

The GeForce GT 640 DDR3 should be a small bit (more or less 15%) more effective at texture filtering than the Radeon HD 4850 512MB. (explain)

GeForce GT 640 DDR3		28800 Mtexels/sec
Radeon HD 4850 512MB		25000 Mtexels/sec
	Difference: 3800 (15%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the GeForce GT 640 DDR3 is superior to the Radeon HD 4850 512MB, by a large margin. (explain)

GeForce GT 640 DDR3		14400 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 4400 (44%)

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 (in units of megabytes per second) that can be transferred past the external memory interface within a second. It's calculated by multiplying the interface width by its memory speed. If it uses DDR type RAM, it should be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per second. This number is calculated by multiplying the total texture units by the core clock speed of the chip. The better the texel rate, 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 could possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the max fill rate.