Unbuffered Dimms (Udimms) - Lenovo System x3250 M4 Installation And Service Manual

– aa is the CAS latency, in clocks at maximum operating frequency
– bb is the JEDEC SPD Revision Encoding and Additions level
– cc is the reference design file for the design of the DIMM
Notes:
1. To determine the type of a DIMM, see the label on the DIMM. The information on the label is in the
format xGB nRxx PC3v-xxxxxx-xx-xx-xx. The numeral in the sixth numerical position indicates
whether the DIMM is single-rank (n=1) or dual-rank (n=2).
2. The amount of usable memory is reduced, depending on the system configuration. A certain
amount of memory must be reserved for system resources. To view the total amount of installed
memory and the amount of configured memory, run the Setup utility. For additional information, see
"Configuring the server" on page 62.

Unbuffered DIMMs (UDIMMs)

The following notes provide information that you must consider when you install UDIMMs.
• The memory channels run at the lowest common frequency of the DIMMs installed.
• The UDIMM options that are available for the server are 1 GB, 2 GB, 4 GB, and 8 GB (when available)
DIMMs.
• The server supports up to two single-rank or dual-rank UDIMMs per channel.
• The following table lists the supported UDIMM population.
Table 7. Supported UDIMM population per channel
DIMM connectors
per channel
2
2
• The following table lists the maximum DIMM population using ranked UDIMMs.
Table 8. Maximum memory population using ranked UDIMMs (depending on your model)
Number of UDIMMs
4
4
4
4
• The following table shows the UDIMM memory population rule to optimize the system performance.
Table 9. UDIMM population rule
DIMM connector 1
Populated
Populated
Populated
46
Lenovo System x3250 M4 Installation and Service Guide
DIMMs installed in
each channel DIMM type
1 Unbuffered DDR3
ECC
2 Unbuffered DDR3
ECC
DIMM type
Single-rank UDIMMs
Dual-rank UDIMMs
Dual-rank UDIMMs
Dual-rank UDIMMs
DIMM connector 2
Empty
Empty
Populated
DIMM speed
1066, 1333, 1600
1066, 1333, 1600
Size
1 GB
2 GB
4 GB
8 GB
DIMM connector 3
Empty
Populated
Populated
Ranks per DIMM
(any combination)
Single-rank,
dual-rank
Single-rank,
dual-rank
Total memory
4 GB
8 GB
16 GB
32 GB
DIMM connector 4
Empty
Empty
Populated