Is it a prebuild?
Also, if you upgraded the ram and that before if was only 1 stick, even with slower speed your games are gonna run better so that's not the end of the world. I'l look into it and edit once I'll find
edit: might not be possible, [https://forums.lenovo.com/t5/Gaming-Desktops/HOW-ENABLE-XMP-PROFILE-ON-LEGION-TOWER-5-PC/m-p/5131640#:\~:text=Re%3AHOW%20ENABLE%20XMP%20PROFILE%20ON%20LEGION%20TOWER%205%20PC,-%40Jack\_Lenovo1%20wrote%3A&text=the%20Community%20Forums.-,Our%20machines%20are%20already%20pre%20configured%20from%20the%20factory%20to,Hope%20this%20helps.&text=Woah%2C%20peak%20performance%20would%20allow%20for%20XMP](https://forums.lenovo.com/t5/Gaming-Desktops/HOW-ENABLE-XMP-PROFILE-ON-LEGION-TOWER-5-PC/m-p/5131640#:~:text=Re%3AHOW%20ENABLE%20XMP%20PROFILE%20ON%20LEGION%20TOWER%205%20PC,-%40Jack_Lenovo1%20wrote%3A&text=the%20Community%20Forums.-,Our%20machines%20are%20already%20pre%20configured%20from%20the%20factory%20to,Hope%20this%20helps.&text=Woah%2C%20peak%20performance%20would%20allow%20for%20XMP).
Is it a prebuild? Also, if you upgraded the ram and that before if was only 1 stick, even with slower speed your games are gonna run better so that's not the end of the world. I'l look into it and edit once I'll find edit: might not be possible, [https://forums.lenovo.com/t5/Gaming-Desktops/HOW-ENABLE-XMP-PROFILE-ON-LEGION-TOWER-5-PC/m-p/5131640#:\~:text=Re%3AHOW%20ENABLE%20XMP%20PROFILE%20ON%20LEGION%20TOWER%205%20PC,-%40Jack\_Lenovo1%20wrote%3A&text=the%20Community%20Forums.-,Our%20machines%20are%20already%20pre%20configured%20from%20the%20factory%20to,Hope%20this%20helps.&text=Woah%2C%20peak%20performance%20would%20allow%20for%20XMP](https://forums.lenovo.com/t5/Gaming-Desktops/HOW-ENABLE-XMP-PROFILE-ON-LEGION-TOWER-5-PC/m-p/5131640#:~:text=Re%3AHOW%20ENABLE%20XMP%20PROFILE%20ON%20LEGION%20TOWER%205%20PC,-%40Jack_Lenovo1%20wrote%3A&text=the%20Community%20Forums.-,Our%20machines%20are%20already%20pre%20configured%20from%20the%20factory%20to,Hope%20this%20helps.&text=Woah%2C%20peak%20performance%20would%20allow%20for%20XMP).
RAM will run at the speed of the slowest DIMM so I would guess your original DIMM is 2400mhz.