Radeon HD 3850 256MB vs Radeon HD 4850 512MB

Intro

Compare those specs to the Radeon HD 4850 512MB, which uses a 55 nm design. AMD has set the core speed at 625 MHz. The GDDR3 memory runs at a speed of 993 MHz on this particular model. It features 800(160x5) SPUs as well as 40 Texture Address Units and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3850 256MB		75 Watts
Radeon HD 4850 512MB		110 Watts
	Difference: 35 Watts (47%)

Memory Bandwidth

Theoretically speaking, the Radeon HD 4850 512MB will be 20% quicker than the Radeon HD 3850 256MB overall, because of its greater data rate. (explain)

Radeon HD 4850 512MB		63552 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 10560 (20%)

Texel Rate

The Radeon HD 4850 512MB should be a lot (about 134%) better at texture filtering than the Radeon HD 3850 256MB. (explain)

Radeon HD 4850 512MB		25000 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 14312 (134%)

Pixel Rate

The Radeon HD 3850 256MB should be a little bit (approximately 7%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 512MB, and also will be able to handle higher screen resolutions without losing too much performance. (explain)

Radeon HD 3850 256MB		10688 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 688 (7%)

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 data (counted in megabytes per second) that can be moved past the external memory interface within a second. The number is calculated by multiplying the bus width by the speed of its memory. If the card has DDR type RAM, it should be multiplied by 2 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 texture map elements (texels) that are processed in one second. This is calculated by multiplying the total amount of texture units 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 most pixels the video card could possibly record to the local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel output rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the maximum fill rate.