[NAME]  Please press the blue Accept as Solution button below if this post answers your question. Bios must be F2 SATA OPERATION Set for AHCI to F12 Boot from DVD.    HOWEVER I would not be installing 7. OEM Windows 10 DVD works fine for install with the I dont have a key option then you activate using the HOME COA Key. The SLP key in bios cannot be used to activate. What is an SLP product key? A System Locked Pre-installation key, or BIOS key, is a product key that does NOT require activation or being online when using DELL OEM disks.  Windows 8 and 10 require being online to activate with a Key from Microsoft or the COA Key on the unit.  660 might have windows 8 key in bios which means you cannot activate 7 because you must use DELL OEM 7 media. DELL OEM SLP 7 Keys OEM 10 media will install and must be activated online. OEM WIN10 DVD   [IMAGE]    
I want to try to reinstall Windows 7 Home Premium on Inspiron 660s because I changed new hard drives.  Unfortunately the Dell OS recovery tool refuses to recognize either the service tag or express code. I bought the computer in 2012.
Inpiron 660s new hard drive