Silicon Graphics Inc. has narrowed its fourth-quarter revenue estimate from $238 million to $242 million for the fiscal fourth quarter that ended June 27.

In April the maker of workstations and other high-end computers had forecast fourth-quarter revenue of $225 million to $245 million.

The Mountain View-based company posted revenue of $284.5 million in the same period a year ago.

Silicon Graphics also said Thursday it projects a fourth-quarter operating loss of $38 million to $42 million, including restructuring and non-cash impairment charges of about $11 million to $13 million.

Without these charges, the operating loss is expected to be about $28 million to $32 million, within the range of the company's expectations, Silicon Graphics said.