As I remember there is no server called the Digital Server 5000, but there is a Digital Server 5300 which is alpha-based but the CPU's are restricted for use on Windows only. Tru64 will panic with "unsupported system" when it load kernel. There is ways to get around this, but I can't tell you how.
The other server this could be is a Digital ZX5000 which is intel based and can not be used for Tru64.