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 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

Theoretically speaking, the Radeon HD 7870 is 23% quicker than the Radeon HD 4890 1GB in general, due to its higher bandwidth. (explain)

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

Texel Rate

The Radeon HD 7870 is much (approximately 100%) more effective at AF 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 is much (about 100%) more effective at anti-aliasing than the Radeon HD 4890 1GB, and able to handle higher resolutions better. (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: Memory bandwidth is the maximum amount of information (in units of megabytes per second) that can be moved across the external memory interface in one second. It is worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR type memory, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the 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 amount of texture map elements (texels) that can be applied in one second. This is worked out by multiplying the total number of texture units of the card by the core clock speed of the chip. The better this number, the better the graphics card will be at texture filtering (anisotropic filtering - AF). It is measured in millions of texels in a second.

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