Can i use my old windows 7 key

[MunteeHD]

i have an acer aspire ax3810 which , when bought came with windows 7, i recently upgraded to windows 10 and wanted to know if i could use the windows 7 key stuck to the side of the box in my new build
if so how would i go about downloading windows 7 on my new pc build without a cd

 

[Darkbreeze]

No. If it's a new build, using a different motherboard than the Windows 7 product key is registered to, it will not work. If it's the same motherboard that Windows 7 is registered to, and you just want to do a clean install of Windows 10, then yes, you can do that.