Radeon HD 3870 1GB vs Radeon HD 7770

Intro

Compare all that to the Radeon HD 7770, which comes with a clock speed of 1000 MHz and a GDDR5 memory frequency of 1125 MHz. It also features a 128-bit memory bus, and makes use of a 28 nm design. It is comprised of 640 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 7770		80 Watts
Radeon HD 3870 1GB		106 Watts
	Difference: 26 Watts (33%)

Memory Bandwidth

Both cards have exactly the same bandwidth, so in theory they should have the same performance. (explain)

Texel Rate

The Radeon HD 7770 is a lot (more or less 223%) better at texture filtering than the Radeon HD 3870 1GB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 3870 1GB		12400 Mtexels/sec
	Difference: 27600 (223%)

Pixel Rate

The Radeon HD 7770 will be a lot (about 29%) faster with regards to anti-aliasing than the Radeon HD 3870 1GB, and also capable of handling higher screen resolutions without losing too much performance. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 3870 1GB		12400 Mpixels/sec
	Difference: 3600 (29%)

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly record to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number of ROPs by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on lots of other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.