Radeon HD 4890 1GB vs Radeon HD 6770

Intro

Compare that to the Radeon HD 6770, which has a core clock frequency of 900 MHz and a GDDR5 memory speed of 1050 MHz. It also makes use of a 128-bit memory bus, and makes use of a 40 nm design. It is comprised of 800 SPUs, 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 6770		108 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 82 Watts (76%)

Memory Bandwidth

Theoretically, the Radeon HD 4890 1GB should perform quite a bit faster than the Radeon HD 6770 overall. (explain)

Radeon HD 4890 1GB		124800 MB/sec
Radeon HD 6770		67200 MB/sec
	Difference: 57600 (86%)

Texel Rate

The Radeon HD 4890 1GB is a little bit (approximately 11%) more effective at AF than the Radeon HD 6770. (explain)

Radeon HD 4890 1GB		40000 Mtexels/sec
Radeon HD 6770		36000 Mtexels/sec
	Difference: 4000 (11%)

Pixel Rate

The Radeon HD 4890 1GB should be just a bit (about 11%) faster with regards to FSAA than the Radeon HD 6770, and also should be capable of handling higher screen resolutions better. (explain)

Radeon HD 4890 1GB		16000 Mpixels/sec
Radeon HD 6770		14400 Mpixels/sec
	Difference: 1600 (11%)

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 in one second. It's worked out by multiplying the bus width by its memory speed. In the case of DDR RAM, the result should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher 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 texture map elements (texels) that can be applied in one second. This figure is worked out by multiplying the total amount of texture units of the card by the core clock speed of the chip. The higher the texel rate, the better the card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly record to its local memory in a second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on quite a few other factors, especially the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the max fill rate.