Radeon HD 4790 vs Radeon HD 4850 X2 512MB

Intro

The Radeon HD 4790 features a GPU core clock speed of 600 MHz, and the 512 MB of GDDR5 memory runs at 800 MHz through a 256-bit bus. It also is comprised of 640(128x5) SPUs, 32 Texture Address Units, and 16 Raster Operation Units.

Compare those specs to the Radeon HD 4850 X2 512MB, which comes with a clock frequency of 625 MHz and a GDDR3 memory speed of 993 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 ROPs.

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 4850 X2 512MB Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Specifications

Model	Radeon HD 4790	Radeon HD 4850 X2 512MB
Manufacturer	ATi	ATi
Year	2009	Nov 7, 2008
Code Name	RV790	R700
Fab Process	55 nm	55 nm
Bus	PCIe 2.0 x16	PCIe 2.0 x16 (PCIe bridge)
Memory	512 MB	512 MB (x2)
Core Speed	600 MHz	625 MHz (x2)
Shader Speed	N/A MHz	(N/A) MHz (x2)
Memory Speed	800 MHz	993 MHz (x2)
Unified Shaders	640(128x5)	800(160x5) (x2)
Texture Mapping Units	32	40 (x2)
Render Output Units	16	16 (x2)
Bus Type	GDDR5	GDDR3
Bus Width	256-bit	256-bit (x2)
DirectX Version	DirectX 10.1	DirectX 10.1
OpenGL Version	OpenGL 3.0	OpenGL 3.0
Power (Max TDP)	N/A watts	250 watts
Shader Model	4.1	4.1
Bandwidth	102400 MB/sec	127104 MB/sec
Texel Rate	19200 Mtexels/sec	50000 Mtexels/sec
Pixel Rate	9600 Mpixels/sec	20000 Mpixels/sec

Memory Bandwidth: Memory bandwidth is the largest amount of data (measured in MB per second) that can be transferred past the external memory interface in one second. It's worked out by multiplying the card's interface width by the speed of its memory. If the card has DDR RAM, it should be multiplied by 2 again. If it uses DDR5, multiply by 4 instead. The better the memory bandwidth, the better the card will be in general. It especially helps with anti-aliasing, HDR and high resolutions.

Texel Rate: Texel rate is the maximum number of texture map elements (texels) that can be processed per second. This figure is worked out by multiplying the total number of texture units by the core 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 one second.

Pixel Rate: Pixel rate is the most pixels the graphics card could possibly record to the local memory in a second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Render Output Units by the clock speed of the card. 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 of the card - the lower the bandwidth is, the lower the potential to get to the maximum fill rate.