  [NAME] Researcher  Please press the blue Accept as Solution button below if the post answers your question. 9020 models in general have WIN8 KEY in  bios. If thats the case it won't ask for a key. Install with ANY WIN10 media via the "I dont have a key option" for home or pro depending on what the coa has. Once installed you MUST GO ONLINE to activate. 
Hello I'd like to buy a used Optiplex 9020 which has an original COA for Windows 7 Pro I bought a legimate Full Install Dell Disc for Windows 10 Pro (which usually required the old COA on the machine). However this machine (owned by someone else), had a hard drive originally formatted with W7 Pro. What do I need to do to format a New System Drive for this machine (which has an original COA for Windows 7 Pro)? Thank You
Formatting W10 Pro In New Drive - Different Computer With COA for Windows 7 Pro