Radeon HD 4890 1GB vs Radeon HD 7870

Intro

Compare those specs to the Radeon HD 7870, which has a clock frequency of 1000 MHz and a GDDR5 memory speed of 1200 MHz. It also uses a 256-bit bus, and makes use of a 28 nm design. It is comprised of 1280 SPUs, 80 Texture Address Units, and 32 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Power Consumption (Max TDP)

Radeon HD 7870		175 Watts
Radeon HD 4890 1GB		190 Watts
	Difference: 15 Watts (9%)

Memory Bandwidth

In theory, the Radeon HD 7870 should be a lot faster than the Radeon HD 4890 1GB overall. (explain)

Radeon HD 7870		153600 MB/sec
Radeon HD 4890 1GB		124800 MB/sec
	Difference: 28800 (23%)

Texel Rate

The Radeon HD 7870 is a lot (approximately 100%) better at anisotropic filtering than the Radeon HD 4890 1GB. (explain)

Radeon HD 7870		80000 Mtexels/sec
Radeon HD 4890 1GB		40000 Mtexels/sec
	Difference: 40000 (100%)

Pixel Rate

If using lots of anti-aliasing is important to you, then the Radeon HD 7870 is a better choice, by a large margin. (explain)

Radeon HD 7870		32000 Mpixels/sec
Radeon HD 4890 1GB		16000 Mpixels/sec
	Difference: 16000 (100%)

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 data (measured in megabytes per second) that can be transported past the external memory interface within a second. The number is calculated by multiplying the card's interface width by the speed of its memory. In the case of DDR RAM, it must 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, High Dynamic Range and higher screen resolutions.

Texel Rate: Texel rate is the maximum texture map elements (texels) that are applied per second. This number is worked out by multiplying the total amount of texture units 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 per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card could possibly write to the local memory in one second - measured in millions of pixels per second. Pixel rate is calculated by multiplying the amount of Raster Operations Pipelines by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.