With the launch of Rocket Lake-S, Intel started using gear modes on its memory controller. The idea here is that in Gear 1, the memory controller operates at the same frequency as the system memory, using a 1:1 ratio. This offers the lowest possible memory latency. In Gear 2 on the other hand, the memory controller runs at half the frequency of the memory, resulting in a 2:1 ratio. This allows the memory to achieve a much higher frequency -- at the expense of latency.
Tom's Hardware speculates the memory gears could start playing a much bigger role once DDR5 hits the market. At the moment, it's still too early to speculate about the implications here. But we could see more higher frequencies in situations where this is more important than low latency.
What we don't know yet is how gears will be implemented on Alder Lake. Intel could be upgrading the memory controller on Alder Lake, which would change the capabilities of each gear ratio. Or Intel might be using the same controller found on current Rocket Lake CPUs, we really don't know at this time. -- Tom's HardwareAlder Lake is scheduled to arrive before the end of this year.