Radeon HD 3850 256MB vs Radeon HD 4850 1GB

Intro

Compare all that to the Radeon HD 4850 1GB, which comes with a clock frequency of 625 MHz and a GDDR4 memory frequency of 993 MHz. It also uses a 256-bit memory bus, and makes use of a 55 nm design. It features 800(160x5) SPUs, 40 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 3850 256MB		75 Watts
Radeon HD 4850 1GB		110 Watts
	Difference: 35 Watts (47%)

Memory Bandwidth

The Radeon HD 4850 1GB should theoretically be just a bit faster than the Radeon HD 3850 256MB in general. (explain)

Radeon HD 4850 1GB		63552 MB/sec
Radeon HD 3850 256MB		52992 MB/sec
	Difference: 10560 (20%)

Texel Rate

The Radeon HD 4850 1GB will be a lot (approximately 134%) more effective at anisotropic filtering than the Radeon HD 3850 256MB. (explain)

Radeon HD 4850 1GB		25000 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 14312 (134%)

Pixel Rate

The Radeon HD 3850 256MB is a little bit (about 7%) faster with regards to full screen anti-aliasing than the Radeon HD 4850 1GB, and will be able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 3850 256MB		10688 Mpixels/sec
Radeon HD 4850 1GB		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 maximum amount of information (counted in MB per second) that can be transported across the external memory interface within a second. The number is worked out by multiplying the bus width by its memory clock speed. If it uses DDR type memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the bandwidth is, the faster 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 in one second. This number is calculated by multiplying the total texture units by the core speed of the chip. The higher the texel rate, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip can possibly write to its local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the ability to reach the maximum fill rate.