2400MHz without XMP support
2400MHz without XMP support
Did they verify the 2400MHz RAM was operating at that frequency before you tried the 2133MHz unit? It's typical for manufacturers to fit faster RAM than the system can handle. Consider resetting the BIOS using the 2400MHz stick, which may prompt a memory retraining process.
I checked before trying my 2133MHz because I planned to add another 2400MHz. After testing the original 2133MHz unit, it returned to its initial setting from when the laptop was first purchased. I didn’t modify the RAM at all, so it still shows 2133MHz even after resetting the BIOS.
This change from 2133 to 2400MHz won’t have a significant impact, probably only a few percent at most. It’s not going to matter much. At least these are the results I’ve observed in tests.