In recent years, it's become common knowledge that Intel's CPUs run nicely with highly overclocked RAM, such as DDR5-7200. Not every chip does, of course, as it's not just about the processor, but having the right motherboard and RAM combination.
Going much faster than 7,000 MT/s typically required buying special 'hand-picked' RAM modules and having an ultra-expensive motherboard.
With the launch of Arrow Lake, however, Intel introduced support for a new type of memory. Well, the DRAM itself is still good ol' DDR5, but these new kits sport something extra on their circuit boards—a clock driver chip or CKD for short.
This tiny integrated circuit takes the memory signals transmitted by the motherboard and stores them momentarily in order to tidy up and realign the signals, so that each RAM module on the circuit board gets its signal at the right voltage and timings.
This ensures everything is stable, when the clock speeds are ramped up. Such RAM kits are called CUDIMMs (Clocked Unbuffered Dual Inline Memory Modules) and they're the hottest thing in the RAM market right now.