Radeon HD 4870 512MB vs Radeon HD 6790

Intro

Compare those specs to the Radeon HD 6790, which has a core clock frequency of 840 MHz and a GDDR5 memory speed of 1050 MHz. It also makes use of a 256-bit memory bus, and makes use of a 40 nm design. It features 800 SPUs, 40 TAUs, and 16 ROPs.

Display Graphs

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Power Usage and Theoretical Benchmarks

Both cards have the same power consumption.

Memory Bandwidth

Theoretically speaking, the Radeon HD 6790 will be 17% quicker than the Radeon HD 4870 512MB overall, due to its greater bandwidth. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4870 512MB		115200 MB/sec
	Difference: 19200 (17%)

Texel Rate

The Radeon HD 6790 will be a bit (more or less 12%) more effective at anisotropic filtering than the Radeon HD 4870 512MB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4870 512MB		30000 Mtexels/sec
	Difference: 3600 (12%)

Pixel Rate

If running with a high screen resolution is important to you, then the Radeon HD 6790 is superior to the Radeon HD 4870 512MB, but not by far. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4870 512MB		12000 Mpixels/sec
	Difference: 1440 (12%)

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 data (counted in megabytes per second) that can be moved over the external memory interface in one second. The number is worked out by multiplying the bus width by the speed of its memory. If the card has DDR memory, the result should be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the faster the card will be in general. It especially helps with AA, HDR and high resolutions.

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

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card can possibly write to its 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 core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel fill rate is also dependant on many other factors, especially the memory bandwidth - the lower the memory bandwidth is, the lower the potential to get to the max fill rate.