Radeon HD 3850 256MB vs Radeon HD 4850 1GB

Intro

The Radeon HD 3850 256MB features a clock frequency of 668 MHz and a GDDR3 memory speed of 828 MHz. It also features a 256-bit bus, and makes use of a 55 nm design. It is comprised of 320(64x5) SPUs, 16 Texture Address Units, and 16 Raster Operation Units.

Compare those specs to the Radeon HD 4850 1GB, which features GPU clock speed of 625 MHz, and 1024 MB of GDDR4 memory set to run at 993 MHz through a 256-bit bus. It also features 800(160x5) Stream Processors, 40 Texture Address Units, 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 3850 256MB Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Radeon HD 4850 1GB Amazon.com Other US-based stores Amazon.co.uk Amazon.de Amazon.fr

Specifications

Model	Radeon HD 3850 256MB	Radeon HD 4850 1GB
Manufacturer	ATi	ATi
Year	Nov 19, 2007	Jun 25, 2008
Code Name	RV670 PRO	RV770 PRO
Fab Process	55 nm	55 nm
Bus	PCIe 2.0 x16/AGP 8x	PCIe 2.0 x16
Memory	256 MB	1024 MB
Core Speed	668 MHz	625 MHz
Shader Speed	N/A MHz	(N/A) MHz
Memory Speed	828 MHz	993 MHz
Unified Shaders	320(64x5)	800(160x5)
Texture Mapping Units	16	40
Render Output Units	16	16
Bus Type	GDDR3	GDDR4
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)	75 watts	110 watts
Shader Model	4.1	4.1
Bandwidth	52992 MB/sec	63552 MB/sec
Texel Rate	10688 Mtexels/sec	25000 Mtexels/sec
Pixel Rate	10688 Mpixels/sec	10000 Mpixels/sec

Memory Bandwidth: Bandwidth is the max amount of information (in units of MB per second) that can be transferred across the external memory interface in one second. It's worked out by multiplying the bus width by its memory speed. If the card has DDR type memory, it must be multiplied by 2 once again. If it uses DDR5, multiply by ANOTHER 2x. The better the card's memory bandwidth, the better 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 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 per second.

Pixel Rate: Pixel rate is the maximum amount of pixels that the graphics chip could possibly record to its local memory per second - measured in millions of pixels per second. The number is calculated by multiplying the amount of Render Output Units by the the core speed of the card. ROPs (Raster Operations Pipelines - also called Render Output Units) are responsible for filling the screen with pixels (the image). The actual pixel rate is also dependant on lots of other factors, most notably the memory bandwidth of the card - the lower the bandwidth is, the lower the ability to get to the maximum fill rate.