Radeon HD 3870 X2 512MB vs Radeon HD 4850 512MB

Intro

The Radeon HD 3870 X2 512MB makes use of a 55 nm design. ATi has clocked the core speed at 825 MHz. The GDDR3 RAM is set to run at a frequency of 900 MHz on this specific model. It features 320(64x5) SPUs as well as 16 Texture Address Units and 16 Rasterization Operator Units.

Compare that to the Radeon HD 4850 512MB, which uses a 55 nm design. ATi has clocked the core speed at 625 MHz. The GDDR3 RAM is set to run at a frequency of 993 MHz on this model. It features 800(160x5) SPUs along with 40 Texture Address Units and 16 Rasterization Operator 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 3870 X2 512MB Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

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

Specifications

Model	Radeon HD 3870 X2 512MB	Radeon HD 4850 512MB
Manufacturer	ATi	ATi
Year	Jan 28, 2008	Jun 25, 2008
Code Name	R680	RV770 PRO
Fab Process	55 nm	55 nm
Bus	PCIe 2.0 x16/(internal PCIe 1.1 x16)	PCIe 2.0 x16
Memory	512 MB (x2)	512 MB
Core Speed	825 MHz (x2)	625 MHz
Shader Speed	N/A MHz (x2)	(N/A) MHz
Memory Speed	900 MHz (x2)	993 MHz
Unified Shaders	320(64x5) (x2)	800(160x5)
Texture Mapping Units	16 (x2)	40
Render Output Units	16 (x2)	16
Bus Type	GDDR3	GDDR3
Bus Width	256-bit (x2)	256-bit
DirectX Version	DirectX 10.1	DirectX 10.1
OpenGL Version	OpenGL 3.0	OpenGL 3.0
Power (Max TDP)	N/A watts	110 watts
Shader Model	4.1	4.1
Bandwidth	115200 MB/sec	63552 MB/sec
Texel Rate	26400 Mtexels/sec	25000 Mtexels/sec
Pixel Rate	26400 Mpixels/sec	10000 Mpixels/sec

Memory Bandwidth: Bandwidth is the maximum amount of data (measured in megabytes per second) that can be transferred past the external memory interface within a second. It's worked out by multiplying the bus width by the speed of its memory. In the case of DDR RAM, it should be multiplied by 2 once again. If DDR5, multiply by ANOTHER 2x. The higher the memory bandwidth, 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 amount of texture map elements (texels) that are processed per second. This is calculated by multiplying the total amount of texture units of the card by the core clock speed of the chip. The better the texel rate, the better the card will be at handling texture filtering (anisotropic filtering - AF). It is measured in millions of texels processed per second.

Pixel Rate: Pixel rate is the maximum number of pixels the video card can possibly record to its local memory per second - measured in millions of pixels per second. Pixel rate is worked out by multiplying the amount of colour ROPs by the the core speed of the card. ROPs (Raster Operations Pipelines - aka Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel fill rate also depends on many other factors, most notably the memory bandwidth - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.