As part of the annual Hot Chips Technology Symposium, IBM introduced a new open Memory Interface (OMI). It is positioned as a more advanced alternative to DDR memory. Among the key advantages, the manufacturer claims about the greater bandwidth and the possibility of increasing the amount of memory.
One feature of the OMI interface is the lack of a memory controller in the host. Instead, a controller on a relatively small DIMM card is used. This solution simplifies the development of the processor and reduces its heating. According to IBM, the removal of the controller on a separate Board allows you to install up to 4 TB of memory running at a speed of about 320 GB/s, or up to 512 GB of memory capable of transferring data at a speed of up to 650 GB/s.
Removing the memory controller onto a separate board has negative consequences, including an additional delay of at least 4 nanoseconds and the dissipation of about 4 watts of energy. However, this is about half compensated for by less heat generated by the host by removing the PHY DDR from the host.
IBM expects future controllers to use the OMI interface with DRAM as an alternative to the increasingly popular but still expensive and energy-intensive HBM memory. The manufacturer intends to use the new interface in Power 9 processors, which will appear in 2020. Then, in IBM Power 10 chips, it is planned to switch to converters that support data transfer at speeds of up to 32-50 Gbit/s.