Intel Pentium III 667
Just like this Pentium III 667 but then in slot 1 form.
Two things can be noticed about this CPU: one is that it has a big passive heatsink attached. If I remember correctly this CPU was pulled from an HP/Compaq system that used a shroud solution to pull air from the case, through the CPU heatsink and out of the back. A nice way to minimize fans and to avoid the use of fragile 40mm fans.
Another thing is it's early production date. The Intel Coppermine was introduced in October 1999 and it's release price was 605$. This CPU was part of quite an expensive and fast (at the time) computer!