Radeon HD 4870 1GB vs Radeon HD 4890 2GB

Intro

The Radeon HD 4870 1GB comes with clock speeds of 750 MHz on the GPU, and 900 MHz on the 1024 MB of GDDR5 memory. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator Units.

Compare that to the Radeon HD 4890 2GB, which comes with GPU clock speed of 1000 MHz, and 2048 MB of GDDR5 RAM set to run at 975 MHz through a 256-bit bus. It also is comprised of 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 1GB 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 1GB	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	1024 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: Bandwidth is the max amount of information (counted in megabytes per second) that can be transferred across the external memory interface in a second. It is worked out by multiplying the interface width by the speed of its memory. If it uses DDR type memory, it should be multiplied by 2 again. If it uses DDR5, multiply by ANOTHER 2x. The better the bandwidth is, the faster the card will be in general. It especially helps with AA, High Dynamic Range and higher screen resolutions.

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

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