I said "max frequency safe", because a friend of mine own 4 cards RX5700 (non XT), keeped them 1 month at -24% power limit, (around 1290-1300MHz GPU core for -24% power limit) and 895MHz memory, everything was flawless, 0 restarts, 0 errors or rig locked. After that he decided to push them all, upper to 920MHz mem, keeping others settings the same, and in couple hours after increase mem at 920MHz, 2 cards from 4, DIED, rog restarted itself and 2 cards unrecognized, cannot load drivers for it, also tested separately on desktop, same sgit, not recognized by drivers, no signal out, etc.  He used as me too, MSI Afterburner. Now 2 cards are go back to warranty.

So, that's why I said "max freq safe", because pusing em up 920MHz for memory, it killed 2 cards.

I keep mines like this (1x 5700 and 4x 5700XT)

https://imgur.com/hTEtXQv