Radeon HD 4890 1GB vs Radeon HD 7870

Intro

Compare those specifications to the Radeon HD 7870, which features a clock speed of 1000 MHz and a GDDR5 memory speed of 1200 MHz. It also makes use of a 256-bit bus, and makes use of a 28 nm design. It is comprised of 1280 SPUs, 80 TAUs, and 32 Raster Operation Units.

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

Performance-wise, the Radeon HD 7870 should theoretically be quite a bit better than the Radeon HD 4890 1GB in general. (explain)

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

Texel Rate

The Radeon HD 7870 should be a lot (more or less 100%) better at texture 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

The Radeon HD 7870 should be quite a bit (approximately 100%) better at anti-aliasing than the Radeon HD 4890 1GB, and also able to handle higher resolutions without slowing down too much. (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 largest amount of data (in units of megabytes per second) that can be transferred past the external memory interface in one second. It's calculated by multiplying the interface width by its memory speed. If the card has DDR type RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, 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 can be processed per second. This figure is worked out by multiplying the total texture units of the card by the core clock speed of the chip. The better the texel rate, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the video card could possibly write to the local memory per second - measured in millions of pixels per second. The figure is calculated by multiplying the amount of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - sometimes also referred to as Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel fill rate also depends on many other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.