Check the memory timings, not just the speed.

For RAM matching the more important is RAM chips rather than the brand on the sticks. Lets say if its Samsung B die from Corsair you can still match pair with another B die kit from Kingston if they have nearly the same timings. Then XMP out of the box usually should have no issues.

For ur case, Gskill is good that you can get a pretty good idea what memory chips are onboard based on the Serial Number. See here for guide https://www.reddit.com/r/overclocking/wiki/....skill_sn_table

So once you find ur Z Royal RAM chip model, go find out if that Z Neo has the same chips or else you may need to search more for compatible RAMS. To note even match pairing the brand makers is no guaranteed success as many ie Micron has different die revision (ie A die, B die, E die, etc) which can also affect XMP stability.

OTOH CL18 is a loose timing sticks so it might still play well with chips from other makers (ie if ur Z Royal is by Samsung, and the other is from Micron or something) but again no guarantees and even XMP at auto setup is more than likely to fail some stability tests.

Good luck hunting!