Xserve fan 1 in fails

Yesterday our xserve dropped off the map. It hosts web sites which are used a lot right now. I went to see to look. All the fans were on max. Server monitor shows that Fan1 in (system board) is 0 RPM. That probably explains the fans on max. But what I don't get, is that the whole server is very erratic, even when running. When I connect with RD, it keeps dropping the connection. Some time later, it will come back. This is even when running from the backup drive. At first I thought it was DNS but all logs are normal and all services running. Has anyone else experienced something like this? Could a dead fan interrupt other services? Other fans are running high, but not in the critical range.