Radeon HD 4790 vs Radeon HD 6850

Intro

The Radeon HD 4790 features a clock speed of 600 MHz and a GDDR5 memory speed of 800 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It features 640(128x5) SPUs, 32 TAUs, and 16 Raster Operation Units.

Compare all of that to the Radeon HD 6850, which comes with GPU core speed of 775 MHz, and 1024 MB of GDDR5 memory set to run at 1000 MHz through a 256-bit bus. It also is comprised of 960 Stream Processors, 48 TAUs, and 32 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 4790 Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Radeon HD 6850 Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Specifications

Model	Radeon HD 4790	Radeon HD 6850
Manufacturer	ATi	ATi
Year	2009	October 2010
Code Name	RV790	Barts Pro
Fab Process	55 nm	40 nm
Bus	PCIe 2.0 x16	PCIe x16
Memory	512 MB	1024 MB
Core Speed	600 MHz	775 MHz
Shader Speed	N/A MHz	(N/A) MHz
Memory Speed	800 MHz	1000 MHz
Unified Shaders	640(128x5)	960
Texture Mapping Units	32	48
Render Output Units	16	32
Bus Type	GDDR5	GDDR5
Bus Width	256-bit	256-bit
DirectX Version	DirectX 10.1	DirectX 11
OpenGL Version	OpenGL 3.0	OpenGL 4.1
Power (Max TDP)	N/A watts	127 watts
Shader Model	4.1	5.0
Bandwidth	102400 MB/sec	128000 MB/sec
Texel Rate	19200 Mtexels/sec	37200 Mtexels/sec
Pixel Rate	9600 Mpixels/sec	24800 Mpixels/sec

Memory Bandwidth: Memory bandwidth is the maximum amount of information (counted in megabytes per second) that can be moved past the external memory interface in a second. It is calculated by multiplying the interface width by its memory clock speed. In the case of DDR type memory, it must be multiplied by 2 again. If DDR5, multiply by ANOTHER 2x. 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 processed per second. This figure is calculated by multiplying the total texture units by the core speed of the chip. The higher this number, the better the video card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels applied per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics card could possibly write to its local memory in one second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the number of colour ROPs by the clock speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for drawing the pixels (image) on the screen. The actual pixel rate also depends on quite a few other factors, especially the memory bandwidth of the card - the lower the bandwidth is, the lower the potential to get to the max fill rate.