HP Integrity BL860C i4 User's & Service Manual page 49

There are 12 DIMMs associated with each processor. Each processor has DIMM pairs A through F. A
processor must installed to access its associated memory. A processor can be installed without memory
as long as one of the processors in the conjoined system has memory.
For best performance, the minimum recommendation is a quad of DIMMs for each processor installed in
a conjoined blade product. For best performance (not required), load only the same type (size) of DIMMs
throughout the system. Uniform memory (selected in the memconfig interleaving options) is supported
with a total memory capacity equal to a "power of two" (loading 4, 8, 16, 32, or 64 DIMMs at a time).
Therefore, for best performance, if using the uniform memory selections, load a quad (even better two
quads) of DIMMs for each processor. To obtain the fastest memory access, load a total memory capacity
equal to a power of four (4, 16, 64).
IMPORTANT:
The system will boot with memory loaded on only one processor. However, from a performance
perspective, this is not a recommended configuration.
To enable Double DRAM chip sparing, for all the DIMMs loaded in the system, use only 4GB, 8GB, or
16GB DIMMs.
The 10GigE LOMs that have jumbo frames enabled require 1GB of main memory for each port (8GB/
server blade). Anything below this minimum results in insufficient memory and a hang either during the
HP-UX boot or during the I/O configuration for the Integrity BL8x0c i4 systems. For example, the minimum
memory configuration for the BL860c i4 is 8GB, for the BL870c i4 is 16GB, and for the BL890c i4 is
32GB.
Minimum memory requirements assume the Flex-10/FlexFabric adapters are not installed. Increase the
minimum required memory by 2GB for each Flex-10/FlexFabric mezzanine card that is installed into the
system.
DIMM pair load order
Figure 1: DIMM quad load order
Optional components 49