Specifications

Product Errata 47
Revision Guide for AMD Athlon™ 64 and AMD Opteron™ Processors
25759 Rev. 3.79 July 2009
86 DRAM Data Masking Feature Can Cause ECC Failures
Description
Under certain conditions, the memory controller fails to generate a DRAM read request when
performing partial writes to an already allocated write combining buffer. Because the DRAM is not
read for these subsequent write requests, the generated ECC bits are incorrect.
Potential Effect on System
Incorrect data can be read back from DRAM.
Suggested Workaround
BIOS should disable the data masking feature when ECC DIMMs are used by setting the DisDatMsk
bit (Northbridge Configuration Register - MSR C001_001F, bit 36).
Fix Planned
Yes