Radeon HD 4770 vs Radeon HD 4850 512MB

Intro

Compare those specs to the Radeon HD 4850 512MB, which features a core clock speed of 625 MHz and a GDDR3 memory frequency of 993 MHz. It also uses a 256-bit memory bus, and uses a 55 nm design. It is made up of 800(160x5) SPUs, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 4770		80 Watts
Radeon HD 4850 512MB		110 Watts
	Difference: 30 Watts (38%)

Memory Bandwidth

Performance-wise, the Radeon HD 4850 512MB should theoretically be quite a bit better than the Radeon HD 4770 overall. (explain)

Radeon HD 4850 512MB		63552 MB/sec
Radeon HD 4770		51200 MB/sec
	Difference: 12352 (24%)

Texel Rate

The Radeon HD 4850 512MB will be a little bit (more or less 4%) faster with regards to anisotropic filtering than the Radeon HD 4770. (explain)

Radeon HD 4850 512MB		25000 Mtexels/sec
Radeon HD 4770		24000 Mtexels/sec
	Difference: 1000 (4%)

Pixel Rate

If running with lots of anti-aliasing is important to you, then the Radeon HD 4770 is the winner, not by a very large margin though. (explain)

Radeon HD 4770		12000 Mpixels/sec
Radeon HD 4850 512MB		10000 Mpixels/sec
	Difference: 2000 (20%)

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 (measured in megabytes per second) that can be transported over the external memory interface in a second. It's worked out by multiplying the card's interface width by its memory clock speed. In the case of DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by 4 instead. The higher the card's memory bandwidth, the better the card will be in general. It especially helps with AA, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are processed in one second. This figure is worked out by multiplying the total number of texture units by the core clock speed of the chip. The higher the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels per second.

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics card can possibly record to its local memory in a second - measured in millions of pixels per second. The figure is worked out by multiplying the number of colour ROPs by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to 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 bandwidth is, the lower the ability to reach the maximum fill rate.