The DDR5 memory spec is due to be published, but details have remained scarce. When JEDEC, the organization responsible for developing memory standards, gets around to it is anyone's guess. Fortunately, South Korea's SK Hynix spilled the beans recently, providing some solid information.
DDR4, or Dynamic Data Rate version 4, came out in 2014. It started out at 1600 Mhz speeds and eventually reached 3200 Mhz at the very high end, with most DRAM in the low 2000 MHz range. At the time, that was enough. Intel's best Xeon processors had eight cores, and AMD was largely irrelevant.
Fast forward to 2020. AMD is thoroughly revitalized and shipping processors with 64 cores, while Intel is shipping 28-core chips and promising a 48-core chip. Ampere is promoting an 80-core Arm server processor, while Marvell has a 96-core Arm processor called ThunderX3.
Thanks to Andy Patrizio (see source)