Radeon HD 4850 1GB vs Radeon HD 7770

Intro

Compare all that to the Radeon HD 7770, which features a GPU core clock speed of 1000 MHz, and 1024 MB of GDDR5 RAM running at 1125 MHz through a 128-bit bus. It also is comprised of 640 Stream Processors, 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 7770		80 Watts
Radeon HD 4850 1GB		110 Watts
	Difference: 30 Watts (38%)

Memory Bandwidth

Theoretically, the Radeon HD 7770 should perform a little bit faster than the Radeon HD 4850 1GB in general. (explain)

Radeon HD 7770		72000 MB/sec
Radeon HD 4850 1GB		63552 MB/sec
	Difference: 8448 (13%)

Texel Rate

The Radeon HD 7770 will be quite a bit (about 60%) faster with regards to anisotropic filtering than the Radeon HD 4850 1GB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4850 1GB		25000 Mtexels/sec
	Difference: 15000 (60%)

Pixel Rate

The Radeon HD 7770 will be quite a bit (approximately 60%) more effective at full screen anti-aliasing than the Radeon HD 4850 1GB, and also able to handle higher resolutions without slowing down too much. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4850 1GB		10000 Mpixels/sec
	Difference: 6000 (60%)

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 data (in units of MB per second) that can be transferred past the external memory interface in a second. It's calculated by multiplying the card's interface width by the speed of its memory. If it uses DDR type RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The better the memory bandwidth, 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 number of texture map elements (texels) that are applied per second. This number is calculated by multiplying the total amount of texture units by the core clock speed of the chip. The better the texel rate, the better the video 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 amount of pixels the video card can possibly write to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the number of Render Output Units by the the core 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 lots of other factors, especially the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to reach the maximum fill rate.