I've received an Asus 751l for repair. The issue was that the client was worried about the heating and disk space. The disk storage was a normal 1TB HHD, so I've recommended to replace it with an SSD drive. Regarding the info that the old drive wasn't used at full capacity I recommended to buy an SSD with 480GB storage. The old drive was replaced with the Crucial BX500 480GB 3D NAND SATA 2.5" SSD . The heating paste for the CPU was really in bad condition, that's why I've replaced it with a new paste. The whole notebook was cleaned. A clean install of Windows 10 Pro OS was done and you won't believe that the boot time when from 15+ sec to 3 sec because of the SSD drive installed. That's awesome.