Intel Xeon 1.2 ES
Not a common find. Engineering samples like this are reserved for big-name OEMs, software companies and reviewers to make sure that a CPU has hardware, software and fanfare to support it on launch. This is a a somewhat early (note the 1999 copyright) sample of the NetBurst Xeon DP with the Willamette-based Foster core in Socket 603 packaging, running at 1.2 GHz, 200 MHz slower than the slowest production model.
This chip, like its production-grade siblings, is easily outdone by the faster and more efficient big-cache (Cascades 2M) Pentium III Xeons in the majority of server applications, and this never-released 1.2 GHz variant is just as much a guaranteed under-performer.
This chip still POSTs and does indeed run at the speed marked on the corner. Markings on the chip indicate it was manufactured in July 2000, 10 months before Foster hit the market, and 4 months before the NetBurst architecture was announced.