Radeon HD 4870 512MB vs Radeon HD 4890 2GB

Intro

The Radeon HD 4870 512MB comes with a clock frequency of 750 MHz and a GDDR5 memory frequency of 900 MHz. It also uses a 256-bit bus, and makes use of a 55 nm design. It is made up of 800(160x5) SPUs, 40 TAUs, and 16 Raster Operation Units.

Compare those specs to the Radeon HD 4890 2GB, which comes with a GPU core clock speed of 1000 MHz, and 2048 MB of GDDR5 RAM running at 975 MHz through a 256-bit bus. It also features 800(160x5) Stream Processors, 40 TAUs, and 16 Raster Operation Units.

Price Comparison

Please note that the price comparisons are based on search keywords, and might not be the exact same card listed on this page. We have no control over the accuracy of their search results.

Radeon HD 4870 512MB Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Radeon HD 4890 2GB Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Specifications

Model	Radeon HD 4870 512MB	Radeon HD 4890 2GB
Manufacturer	ATi	ATi
Year	Jun 25, 2008	Apr 2, 2009
Code Name	RV770 XT	RV790 XT
Fab Process	55 nm	55 nm
Bus	PCIe 2.0 x16	PCIe 2.0 x16
Memory	512 MB	2048 MB
Core Speed	750 MHz	1000 MHz
Shader Speed	N/A MHz	(N/A) MHz
Memory Speed	900 MHz	975 MHz
Unified Shaders	800(160x5)	800(160x5)
Texture Mapping Units	40	40
Render Output Units	16	16
Bus Type	GDDR5	GDDR5
Bus Width	256-bit	256-bit
DirectX Version	DirectX 10.1	DirectX 10.1
OpenGL Version	OpenGL 3.0	OpenGL 3.0
Power (Max TDP)	150 watts	190 watts
Shader Model	4.1	4.1
Bandwidth	115200 MB/sec	124800 MB/sec
Texel Rate	30000 Mtexels/sec	40000 Mtexels/sec
Pixel Rate	12000 Mpixels/sec	16000 Mpixels/sec

Memory Bandwidth: Memory bandwidth is the max amount of data (counted in megabytes per second) that can be moved across the external memory interface within a second. It's calculated by multiplying the bus width by its memory speed. If it uses DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. The higher the card's memory bandwidth, the better 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 processed per second. This is worked out by multiplying the total number of texture units of the card by the core 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 in a second.

Pixel Rate: Pixel rate is the most pixels the video card could possibly record to the local memory per second - measured in millions of pixels per second. The figure is worked out by multiplying the number of Raster Operations Pipelines by the the core clock speed. ROPs (Raster Operations Pipelines - also sometimes called Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel output rate is also dependant on quite a few other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.