HP Integrity rx8620 Installation Guide, Sixth Edition - HP Integrity rx8620 Se - Page 19

Introduction Detailed HP Integrity rx8620 Server Description The HP Integrity rx8620 Server will support DIMMs with densities of 64, 128, 256, and 512Mb for the SDRAM devices. Table 1-2 shows each supported DIMM size, the resulting total server capacity, and the memory component density. Each DIMM is connected to two buffer chips on the cell board. Table 1-2 HP Integrity rx8620 Server DIMMs DIMM Size 256MB 512MB 1GB 2GB 4GB Total HP Integrity rx8620 Server Capacity Memory Component Density 16GB 64Mb 32GB 128Mb 64GB 256Mb 128GB 256GB 512Mb 1024Mb Main Memory Performance Latency to main memory is an important parameter in determining overall system performance. For a server with memory busses at 125MHz, the latency for a page hit is 8.5 cycles (68ns), the latency for a page closed is 11.5 cycles (92ns), and the latency for a page miss is 14.5 cycles (116ns). Valid Memory Configurations The HP Integrity rx8620 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 128GB by filling all 16 DIMM slots on all four 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 1-8 shows the DIMM slot layout on the cell board. See Table 1-3 and Figure 1-8 for DIMM load order and layout on the cell board. Chapter 1 19