hello, i assume you are referring to the msata raid board? the crucial m550's work for sure, but if you wanna get them in a 512gb size they will be longer then the sandisk ones used by asus, but i think some other user here on this board just taped it so it wont move anymore.
i see now that kingston, Transcend and intel released M.2 ssd's as well but im not sure if they will work as well perhaps other rog members know
Links:
intel:
http://www.intel.com/content/www/us/en/solid-state-drives/solid-state-drives-pro-2500-series.htmlKingston:
http://www.kingston.com/en/ssd/s#sm2280s3Transcend:
http://transcend-info.com/Products/No-643even see Adata and micron as well with those m.2 sata ssd's but again im not 100% sure wich will work and wich not, if you decide wich to get let us know cause im thinking about replacing the sandisk ones as well here.
IF you just want a 2.5 inch ssd there are endless possibilities like the samsung evo or 850 pro's