Memory Subsystem; Memory Riser Cards - IBM Power Systems S822LC Technical Overview And Introduction

While NVLink primarily focuses on connecting multiple NVIDIA Tesla P100s together it can
also connect Tesla P100 GPUs with IBM Power CPUs with NVLink support. Figure 1-11 on
page 18 highlights an example of a four-GPU system with dual NVLink-capable CPUs
connected with NVLink. In this configuration, each GPU has 120 combined GB/s bidirectional
bandwidth to the other three GPUs in the system, and 40 GB/s bidirectional bandwidth to a
CPU.
Figure 1-11 CPU to GPU and GPU to GPU interconnect using NVLink

1.8 Memory subsystem

The Power S822LC server is a two-socket system that supports two POWER8 SCM
processor modules. The server supports a maximum of 32 DDR4 RDIMMs slots housed in
eight memory riser cards.
Memory features equate to a riser card with four memory DIMMs. Memory feature codes that
are supported are 16 GB, 32 GB, 64 GB, and 128 GB, and run at speeds of 1600 MHz,
allowing for a maximum system memory of 1024 GB.

1.8.1 Memory riser cards

Memory riser cards are designed to house up to four industry-standard DRAM memory
DIMMs and include a set of components that allow for higher bandwidth and lower latency
communications:
Memory Scheduler
Memory Management (RAS Decisions & Energy Management)
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IBM Power Systems S822LC for High Performance Computing