https://rog.asus.com/forum/showthre...e-memory-kits!-The-meat-and-potatoes-overview
Getting 2 sticks to match up isn't overly hard. Getting 4 sticks from 2 different kits can be problematic. 6 sticks can be a royal pain but chances are mediocre at best. 8 sticks from 2 seperate kits can be near impossible.
If you think of it in terms of ppl, it makes more sense, you take a husband and wife, they meet up with another couple, chances are ok to get 4 friends, but there's a good possibility one husband will be not cool with his wife getting along with the other dude. Make that 3 couples, and chances of problems go way up.
And you have 2 different kits of ram that need to mesh. You might get lucky with some timings adjustments, system agent or memory controller or even ram voltage bumps up 0.05v or you may be totally out of luck.