Radeon HD 3870 1GB vs Radeon HD 7770

Intro

Compare all of that to the Radeon HD 7770, which has a GPU core clock speed of 1000 MHz, and 1024 MB of GDDR5 memory set to run at 1125 MHz through a 128-bit bus. It also 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 3870 1GB		106 Watts
	Difference: 26 Watts (33%)

Memory Bandwidth

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

Texel Rate

The Radeon HD 7770 will be quite a bit (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

If using lots of anti-aliasing is important to you, then the Radeon HD 7770 is a better choice, by far. (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 largest amount of information (counted in megabytes per second) that can be transferred past the external memory interface within a second. It's calculated by multiplying the card's bus width by its memory clock speed. If it uses DDR type RAM, it must be multiplied by 2 again. If DDR5, multiply by 4 instead. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

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

Pixel Rate: Pixel rate is the maximum number of pixels that the graphics chip can possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the number 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 drawing the pixels (image) on the screen. The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth of the card - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.