As Jesper said, you can't to it. There were rumours of Intel putting a small x86 processor in the Itanium for backwards compatibility, but I don't think they did.
Where did you get a server with an Itanium? Are they still even being sold? The Itanium was designed based on the theory of VLIW (very long instruction word) that was popular in the early 1990s. It didn't work out as the theory hoped.
These days, its far easier to get performance with a quad AMD or Intel 64 bit processor.