Hi, The Inspiron 7720/17R (SE) is shipped with mSATA drives with capacity of 32 GB. If you are referring to this hard drive as the one not visible in the list, that is as per the design. The mSATA hard drives are mainly used for caching purposes and to enhance the system performance. In order to re-install the Windows with an mSATA drive present in the system you will have to disable the Accelerate form iRST application.  • Launch Intel RST User Interface from system tray. • Select “Accelerate” Tab, click “Disable acceleration”. • Click “Reset to available” to reset volume. If you have formatted the OS partition already, you will have to install the Windows in AHCI mode. And follow the steps mentioned below. • Boot into OS in AHCI mode • Once the Windows Desktop Appears • Click Start, type Regedit • Right click Regedit and run as administrator HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\iaStorV Change REG DWORD Values of Start from (3) to (0) • Close Regedit • Restart • F2 – Go into bios • Change sata mode from  AHCI to Intel smart Response Technology • Save and exit • After system reboots, download and install the iRST application and Enable the acceleration.  I hope this helps, please do write back in case you need any further assistance. 
Windows 8 will not install on the Inspiron 17R SE 7720. Yet it is listed as being supported here: [URL] I have gone through the step for a clean installation here: [URL]  Then when it comes to point 7, it only lists one hard drive. Shouldn't there be 2 listed? Anyway the hard drive that is listed is named as 'Drive 0 Partition 1' with a total size of 931.5GB. Then when I delete the partition and select the unallocated space it says "We couldn't create a new partition or locate an existing one. For more information see the setup log files.' My only option then is to quit setup, and I don't even know where the log files are found. I have also installed the latest bios located here ( [URL] ) How can I get Windows 8 installed on this?
Cannot install Windows 8 on 7720 (Inspiron 17R (SE))