Radeon HD 4870 2GB vs Radeon HD 7770

Intro

Compare those specifications 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 is comprised of 640 Stream Processors, 40 Texture Address Units, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7770		80 Watts
Radeon HD 4870 2GB		150 Watts
	Difference: 70 Watts (88%)

Memory Bandwidth

In theory, the Radeon HD 4870 2GB is 60% quicker than the Radeon HD 7770 overall, due to its higher bandwidth. (explain)

Radeon HD 4870 2GB		115200 MB/sec
Radeon HD 7770		72000 MB/sec
	Difference: 43200 (60%)

Texel Rate

The Radeon HD 7770 is a lot (about 33%) better at texture filtering than the Radeon HD 4870 2GB. (explain)

Radeon HD 7770		40000 Mtexels/sec
Radeon HD 4870 2GB		30000 Mtexels/sec
	Difference: 10000 (33%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 7770 is a better choice, by far. (explain)

Radeon HD 7770		16000 Mpixels/sec
Radeon HD 4870 2GB		12000 Mpixels/sec
	Difference: 4000 (33%)

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 data (counted in megabytes per second) that can be moved across the external memory interface in one second. It is calculated by multiplying the card's interface width by its memory speed. If the card has DDR memory, it should be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better the card will be in general. It especially helps with AA, HDR and higher screen resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This figure is calculated by multiplying the total number of texture units of the card by the core speed of the chip. The better 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 a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card can possibly write to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Raster Operations Pipelines by the the card's clock speed. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel rate is also dependant on many other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to reach the max fill rate.