Owners Manual

Table 16. Optimal NPS configuration
Number of
DIMMs per
processor
NPS
0 1 2 4
1 X
2 X
3 X
4 X
5 X
6 X
7 X
8 X X
9 X
10 X
11 X
12 X
13 X
14 X
15 X
16 X X
● Recommended NPS setting is marked by X that indicate optimal performance.
● NPS0 is only available for dual processor systems and is the preferred setting.
● The NPS setting that are blank are functional. However, indicate non-optimal performance.
● BIOS default NPS setting is 1.
● UEFI0391 message may be displayed during boot if DIMMs are configured in the blank spaces of the table.
● If the processor does not support the desired NPS setting for a given number of DIMMs, then use default setting (NPS1)
and the UEFI0391 message is displayed.
Memory interleaving population rules
● NPS4: Two channel interleaving
○ This interleaves channel [A and B], [C and D], etc.
○ Each channel within the pair requires at least one equal memory modules populated.
○ Works with three memory modules per channel pair, non-symmetrical module is stacked on top (odd configurations).
○ Any memory channel where one of the two channels is not populated is not interleaved.
○
There is no alternate, as all configurations can be mapped into this mode.
● NPS2: Four channel interleaving
○ This interleaves the four channels on the left or right half of a processor which are channels [A, B, C, D] and [E, F, G, H].
○ All four channels require equal memory modules populated.
○ Each half or interleave set may have different total memory capacity with respect to each other.
● NPS1: Eight channel interleaving
○ This interleaves all channels in a processor [A, B, C, D, E, F, G, H].
○ All channels in a processor require equal memory modules populated.
○ Single processor system creates a single NUMA node for the system.
NOTE:
An exception is allowed when system has 4-channels populated [C, D, G, H] with equal memory allowing the
system to enter NPS1 mode even though all the 8 channels are not populated.
Installing and removing system components 51