Specifications

68 Product Errata
25759 Rev. 3.79 July 2009
Revision Guide for AMD Athlon™ 64 and AMD Opteron™ Processors
108 CPUID Instruction May Return Incorrect Model Number In
Some Processors
Description
The Model Number field (bits 7-4 of the value returned in EAX by CPUID Function 1) may report an
Eh for Revision DH7-CG processors in a 754-pin package. The correct Model Number value for this
processor is Ch. The value read from the Model Number field may not be consistent and could report
a value of Ch or Eh over time.
Note this affects the Model Number field only, all other CPUID fields are unaffected.
Potential Effect on System
The effect of this erratum is similar to a new processor being installed in a system that has not been
updated with BIOS and system software that recognizes the new model number:
• System software dependent on the Model Number field of the CPUID may fail to recognize the
processor causing processor-specific drivers not to load.
• BIOS may fail to recognize the processor and take a safe default action.
• Application software typically does not require knowledge of the Model Number field and
therefore is unaffected.
Suggested Workaround
BIOS and system software should be modified to recognize the Model Number field values of both
Ch and Eh as referring to Revision DH7-CG processors in a 754-pin package.
Fix Planned
Yes