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ATI Radeon HD 4855
The Radeon HD 4855 was a graphics card by ATI, launched in January 2010. Built on the 55 nm process, and based on the RV770 graphics processor, in its RV770 PRO variant, the card supports DirectX 10.1. The RV770 graphics processor is an average sized chip with a die area of 256 mm² and 956 million transistors. Unlike the fully unlocked Radeon HD 4870 Mac Edition, which uses the same GPU but has all 800 shaders enabled, ATI has disabled some shading units on the Radeon HD 4855 to reach the product's target shader count. It features 640 shading units, 32 texture mapping units and 16 ROPs. ATI has placed 512 MB GDDR5 memory on the card, which are connected using a 256-bit memory interface. The GPU is operating at a frequency of 575 MHz, memory is running at 900 MHz.
We recommend the ATI Radeon HD 4855 for gaming with highest details at resolutions up to, and including, 1280x720.
Being a dual-slot card, the ATI Radeon HD 4855 draws power from 1x 6-pin power connectors, with power draw rated at 110 W maximum. Display outputs include: 1x DVI, 1x HDMI, 1x VGA. Radeon HD 4855 is connected to the rest of the system using a PCIe 2.0 x16 interface. The card measures 220 mm in length, and features a dual-slot cooling solution.
||Jan 3rd, 2010
||PCIe 2.0 x16
3600 MHz effective
Rebranded HD 4830 with a HD 4870 PCB
Retail boards based on this design