The Dell Alienware M18x R2 Laptop Supports up to 3 or 4 Drives. (Two or Three 2.5" Solid State Drives or Hard Drives in the Hard Drive Bracket and/or One mSATA Solid State Drive in the Internal mSATA Slot) Note: The Hard Drive bracket supports up to two 9.5mm height drives or up to three 7.0mm height drives.