Hi mate,
The G750 will have two SATA slots where you can install either two SDDs or two HDD or a combination of both. As far as size goes you can install as much as you want depending on the drive, they just need to be 2.5" SATA drives.
The bottom of the G750 is pretty easy to pop open and have a look. From there you can easily see what can be upgrade however you will find two 2.5" SATA slots and the memory slots in there that can be upgraded.
Hope this information helps!
All the best - ASUS ANZ Marketing
