Hi. I'm trying to install Windows 7 on my Dell Inspiron 3147 which shipped with Windows 8.1. I'm using a universal Windows 7 SP1 x64 iso image on USB stick prepared by RUFUS for UEFI. Have tried several other variations on the installation media with same result: Just as the "Starting Windows" animation begins, I get BSOD with "BIOS not fully ACPI compliant" error message. Am currently using latest Bios A07 from Dell. Any suggestions on what to try? My end goal is really to get an activated Windows 7 Pro on here for upgrade to Windows 10 Pro. I'm currently running the Windows 10 Home, but was curious if I could get 10 Pro running without buying it... Also, just curious if there's any way to get Windows 7 x64 on the machine. Any downgrade option from Windows 8.1? Any knowledgeable responses from the forum much appreciated. Thanks!