Radeon HD 4890 2GB vs Radeon HD 7770

Intro

Compare those specifications to the Radeon HD 7770, which has a clock speed of 1000 MHz and a GDDR5 memory frequency of 1125 MHz. It also features a 128-bit memory bus, and uses a 28 nm design. It features 640 SPUs, 40 TAUs, 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 4890 2GB		190 Watts
	Difference: 110 Watts (138%)

Memory Bandwidth

In theory, the Radeon HD 4890 2GB should be 73% faster than the Radeon HD 7770 in general, due to its greater bandwidth. (explain)

Radeon HD 4890 2GB		124800 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 52800 (73%)

Texel Rate

Both cards have the exact same texel fill rate, so in theory they should perform equally good at at AF. (explain)

Pixel Rate

Both cards have exactly the same pixel fill rate, so theoretically they should be equally good at at FSAA, and be capable of handling the same screen resolutions. (explain)

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 data (counted in MB per second) that can be transferred over the external memory interface in one second. The number is calculated by multiplying the card's bus width by the speed of its memory. If the card has DDR type memory, it should be multiplied by 2 once again. If it uses DDR5, multiply by 4 instead. The higher the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly write to its local memory in a second - measured in millions of pixels per second. The figure is calculated by multiplying the amount 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 outputting the pixels (image) to the screen. The actual pixel output rate also depends on quite a few other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.