There are 29 versions of atiumd64.dll in the wild, the latest version being 8.14.10.0784. The average file size is about 4.78 MB. The executable is a .NET framework assembly utilizing the CLR.
atiumd64.dll is the Radeon DirectX 11 Driver for AMD video cards with DirectX acceleration support. This is the 64 bit Windows version of the driver.
United States installs about 62.79% of ATI Technologies Inc. Radeon DirectX Universal Driver.