Sorry not much Asrock bios knowledge, but I would tweak from the XMP setting at 1.50V if that memory is based on Hynix then straight timings is what you should go with, 16-16-16-28 or 17-17-17-32 or 15-15-15-30. Just keep going lower on x and stay above 24 on y (x-x-x-y)

A simple app that you can test the settings is AIDA64, run memory bandwidth test note the scores and improve them.

You can go up to 1.55v but try not to go higher, it will cause fail usually.