Radeon HD 3850 512MB vs Radeon HD 4770

Intro

Compare those specifications to the Radeon HD 4770, which comes with a clock speed of 750 MHz and a GDDR5 memory speed of 800 MHz. It also makes use of a 128-bit memory bus, and uses a 40 nm design. It is comprised of 640(128x5) SPUs, 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 512MB		75 Watts
Radeon HD 4770		80 Watts
	Difference: 5 Watts (7%)

Memory Bandwidth

The Radeon HD 3850 512MB should theoretically perform a little bit faster than the Radeon HD 4770 overall. (explain)

Radeon HD 3850 512MB		52992 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 1792 (4%)

Texel Rate

The Radeon HD 4770 should be quite a bit (more or less 125%) more effective at AF than the Radeon HD 3850 512MB. (explain)

Radeon HD 4770		24000 Mtexels/sec
Radeon HD 3850 512MB		10688 Mtexels/sec
	Difference: 13312 (125%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 4770 is the winner, but it probably won't make a huge difference. (explain)

Radeon HD 4770		12000 Mpixels/sec
Radeon HD 3850 512MB		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 max amount of data (counted in MB per second) that can be transported over the external memory interface within a second. It's calculated by multiplying the bus width by the speed of its memory. In the case of DDR RAM, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This number is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed 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. The number is worked out by multiplying the number of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.