Here are two reliability guidelines for consideration:
• Using fewer, larger DIMMs (for example 6 x 4 GB DIMMs vs. 12 x 2GB DIMMs is generally
more reliable. The more DIMMs installed, the more there are to fail.
• Xeon 5500/5600 Series memory controllers support IBM Chipkill™
technology with x4 DIMMs but not with x8 DIMMs. Chipkill error correction is up to 16X more
effective than standard ECC memory correction.
Pointing out the obvious inconsistency, you can either use x8 memory for greater energy savings,
or x4 memory for greater availability, but not both.
Mixing Chipkill and non-Chipkill memory will
result in no Chipkill protection for any DIMMs.