A kindly reader has taken the trouble to read through Intel's application note literature on the Pentium III and has discovered the company has no faith in its own serial number technology. The reader said: "Today I was perusing through to bone up on CPU ID and PSN of the Pentium III and found the following interesting disclaimers" PSN not reliable From page 16, section 4.0 entitled: "Processor Serial Number": (Identical paragraph in App Note AP-909, March 1999,"Intel Processor Serial Number", Order #245125-001, Page 4-5):- "Processor serial number provides an identifier for the processor, but should not be assumed to be unique in itself. There are potential modes in which erroneous processor serial numbers may be reported. For example, in the event a processor is operated outside its recommended operationg specifications, the processor serial number may not be correctly read from the processor. "Improper BIOS or software operations could yield an inaccurate processor serial number. These events could lead to possible erroneous or duplicate processor serial numbers being reported. System manufacturers can strengthen the robustness of the feature by including redundancy features, or other fault tolerant methods." So there you go. ®