I have a DELL Laptop vostro 3491 . Service Tag - 2P09B53 ( if that helps ) . I came with DDR4-2666 . I recently bought DDR4-3200 ram but HWinfo and windows task manager shows it runs at 2667 mode . And YES 1600Mhz is a jedec profile .
Also check the attached photo .
Also check the attached photo .