Radeon HD 4870 512MB vs Radeon HD 6790

Intro

Compare all that to the Radeon HD 6790, which comes with a clock speed 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 Texture Address Units, and 16 Raster Operation Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Both cards have the same power consumption.

Memory Bandwidth

As far as performance goes, the Radeon HD 6790 should theoretically be a small bit better than the Radeon HD 4870 512MB overall. (explain)

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

Texel Rate

The Radeon HD 6790 is a little bit (approximately 12%) faster with regards to 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 using a high screen resolution is important to you, then the Radeon HD 6790 is superior to the Radeon HD 4870 512MB, though only just barely. (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 largest amount of information (counted in megabytes per second) that can be moved across the external memory interface in a second. It's worked out by multiplying the card's bus width by its memory clock speed. If the card has DDR memory, it must be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the card's 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 applied in one second. This is calculated by multiplying the total number of texture units of the card by the core clock speed of the chip. The higher this number, the better the graphics card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the most pixels that the graphics chip could possibly record to the local memory in one second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the card's clock speed. ROPs (Raster Operations Pipelines - sometimes also referred to as 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, most notably the memory bandwidth - the lower the bandwidth is, the lower the potential to reach the maximum fill rate.