CPU serial number

Question

How do I obtain the serial number of the CPU in a PC?

Answer 1

There is no CPU serial ID (PSN; CPUID edx bit 18 "psn" Processor Serial Number) after Pentium III in Intel CPUs; and there was never any psn in AMD chips:

https://software.intel.com/en-us/forums/watercooler-catchall/topic/308483 (at 2005)

However, keep in mind that only the Pentium III Xeon, Mobile Pentium III and Pentium III processors support the processor serial number feature introduced by the Pentium III processor. No other Intel processor supports the processor serial number feature

https://en.wikipedia.org/wiki/Pentium_III#Controversy_about_privacy_issues

https://en.wikipedia.org/wiki/CPUID#EAX=3:_Processor_Serial_Number

EAX=3: Processor Serial Number See also: Pentium III § Controversy about privacy issues

This returns the processor's serial number. The processor serial number was introduced on Intel Pentium III, but due to privacy concerns, this feature is no longer implemented on later models (the PSN feature bit is always cleared). Transmeta's Efficeon and Crusoe processors also provide this feature. AMD CPUs however, do not implement this feature in any CPU models.