XMP and EXPO are two technologies from Intel and AMD, respectively, that allow system memory to operate at higher speeds than initially rated. It’s quite the trap, as these features are not enabled by default. If you purchase a new RAM kit and wish to install it believing your PC would automatically start using the DDR5-6000 modules at 6,000 MT/s, you’ll be shocked to see that the OS will only report the kit running at a lower JEDEC-rated speed, such as 4,000 MT/s. That’s not a faulty RAM module or few. That’s actually by design unless you change one BIOS/UEFI setting.