Radeon HD 4870 1GB vs Radeon HD 6790

Intro

Compare those specs to the Radeon HD 6790, which makes use of a 40 nm design. AMD has set the core speed at 840 MHz. The GDDR5 RAM is set to run at a frequency of 1050 MHz on this card. It features 800 SPUs along with 40 TAUs and 16 Rasterization Operator Units.

Display Graphs

Hide Graphs

Power Usage and Theoretical Benchmarks

Both cards have the same power consumption.

Memory Bandwidth

Theoretically speaking, the Radeon HD 6790 is 17% quicker than the Radeon HD 4870 1GB in general, because of its higher bandwidth. (explain)

Radeon HD 6790		134400 MB/sec
Radeon HD 4870 1GB		115200 MB/sec
	Difference: 19200 (17%)

Texel Rate

The Radeon HD 6790 is a bit (approximately 12%) more effective at anisotropic filtering than the Radeon HD 4870 1GB. (explain)

Radeon HD 6790		33600 Mtexels/sec
Radeon HD 4870 1GB		30000 Mtexels/sec
	Difference: 3600 (12%)

Pixel Rate

If using high levels of AA is important to you, then the Radeon HD 6790 is the winner, but not by far. (explain)

Radeon HD 6790		13440 Mpixels/sec
Radeon HD 4870 1GB		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 information (in units of MB per second) that can be transported across the external memory interface in one second. It is worked out by multiplying the card's bus width by the speed of its memory. 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 bandwidth is, the faster the card will be in general. It especially helps with anti-aliasing, High Dynamic Range and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that are applied in one second. This is worked out by multiplying the total texture units of the card by the core clock 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 applied in a second.

Pixel Rate: Pixel rate is the maximum amount of pixels the graphics card can possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the amount of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for outputting the pixels (image) to the screen. The actual pixel 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 maximum fill rate.