Site Preparation Guide, Fourth Editon - HP Integrity rx7620 Server

Chapter 1
Introduction
Detailed HP Integrity rx7620 Server Description
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The HP Integrity rx7620 Server supports DIMMs with densities of 64, 128, 256, and 512 Mb for the SDRAM
devices. Table 1-3 shows each supported DIMM size, the resulting total system capacity, and the memory
component density. Each DIMM is connected to two buffer chips on the cell board.
DIMMs must be loaded in sets of four at specific locations. For best performance, HP recommends loading
sets of eight DIMMs.
Main Memory Performance
Latency to main memory is an important parameter in determining overall system performance. With
memory buses running at 125 MHz, the latency for a page hit is 8.5 cycles (68 ns), the latency for a page
closed is 11.5 cycles (92 ns), and the latency for a page miss is 14.5 cycles (116 ns).
Valid Memory Configurations
The HP Integrity rx7620 Server is capable of supporting as little as 0.5GB of main memory using two 256MB
DIMMs installed on one of the cell boards and as much as 64 GB by filling all 16 DIMM slots on both cell
boards with 2GB DIMMs.
DIMMs must be loaded in sets of two at specified locations on the cell board. Two DIMMs are called an
“echelon”, so two echelons would be equivalent to four DIMMs, three echelons would be equivalent to six
DIMMs and so on. The DIMMs must be the same size in an echelon. The DIMMs across all cells in a partition
should have identical memory loaded. Figure 1-9 shows the DIMM slot layout on the cell board. See Table 1-4
for DIMM load order.
Table 1-3 HP Integrity rx7620 Server DIMMs
DIMM Size Total Capacity Memory Component Density
256 MB 8 GB 64 megabit
512 MB 16 GB 128 megabit
1 GB 32 GB 256 megabit
2 GB 64 GB 512 megabit
4 GB 128 GB 1024 megabit