Radeon HD 3850 256MB vs Radeon HD 4770

Intro

Compare those specifications to the Radeon HD 4770, which has GPU core speed of 750 MHz, and 512 MB of GDDR5 memory running at 800 MHz through a 128-bit bus. It also is comprised of 640(128x5) Stream Processors, 32 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 4770		80 Watts
	Difference: 5 Watts (7%)

Memory Bandwidth

The Radeon HD 3850 256MB should in theory be a small bit faster than the Radeon HD 4770 in general. (explain)

Radeon HD 3850 256MB		52992 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 1792 (4%)

Texel Rate

The Radeon HD 4770 should be a lot (approximately 125%) more effective at anisotropic filtering than the Radeon HD 3850 256MB. (explain)

Radeon HD 4770		24000 Mtexels/sec
Radeon HD 3850 256MB		10688 Mtexels/sec
	Difference: 13312 (125%)

Pixel Rate

The Radeon HD 4770 is just a bit (approximately 12%) faster with regards to full screen anti-aliasing than the Radeon HD 3850 256MB, and will be able to handle higher resolutions better. (explain)

Radeon HD 4770		12000 Mpixels/sec
Radeon HD 3850 256MB		10688 Mpixels/sec
	Difference: 1312 (12%)

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 largest amount of information (counted in megabytes per second) that can be moved across the external memory interface within a second. The number is calculated by multiplying the card's bus width by the speed of its memory. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the card's memory bandwidth, 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 can be processed in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core speed of the chip. The better the texel rate, the better the video card will be at 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 the video card could possibly write to its local memory in one second - measured in millions of pixels per second. The figure is calculated by multiplying the number of Render Output Units by the the card's 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 quite a few other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.