GeForce GT 640 DDR3 vs Radeon HD 4850 512MB

Intro

Compare all of that to the Radeon HD 4850 512MB, which comes with a core clock speed of 625 MHz and a GDDR3 memory frequency of 993 MHz. It also uses a 256-bit bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

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 perform a little bit faster than the GeForce GT 640 DDR3 in general. (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 bit (approximately 15%) better 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

The GeForce GT 640 DDR3 should be a lot (more or less 44%) better at anti-aliasing than the Radeon HD 4850 512MB, and will be capable of handling higher screen resolutions more effectively. (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: Bandwidth is the max amount of information (in units of MB per second) that can be moved across the external memory interface in a second. It is calculated by multiplying the card's interface width by its memory speed. If the card has DDR type memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher 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 in one second. This is calculated by multiplying the total texture units of the card by the core speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied in a second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of Render Output Units by the the core clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.