Intel Xeon 5440 (2.83 GHz)
Based on the Harpertown CPU which is basically an improved 45nm version of the Core 2 Duo. The improved architecture features a few enhancements that increase the IPC (Instructions Per Clockcycle) making it a faster CPU even at the same clockspeed.
This particular model has 4 cores that run at 2.83GHz. Not a bad performer in 2008 although one could buy a 3.4GHz part for 3x as much money.