I'm trying to do a clean install of Windows 8.x x64 on an HP Envy 14-2020ep, but for some reason it's not accepting the key from BIOS. It originally came with Windows 7 Home Premium x64. I'm using a USB flash drive created with a couple of rmprepusb tutorials, it contains several Windows ISOs from XP to 8.x, among them Windows 8 x64 (pp_windows_8_x64_dvd_915432.iso) and Windows 8.1 Update x64 (pp_windows_8.1_with_update_x64_dvd_4048346.iso). It allows me to install Windows 8 by asking/detecting key, forcibly install Core or forcibly install Professional by automatically adding a key before booting ISO. I tried all methods without success: 1st one asks for key instead of detecting it from BIOS, and claims it's invalid in both Windows 8 and 8.1U after typing it. Forcibly installing Windows 8.1U Core or Pro and then changing the key to the one in BIOS also claims it's invalid. I'm yet to try installing Windows 8 Core and Pro directly and them using the key, but somehow I think that's also going to fail. I got the key by installing RW-Everything on Windows 7, then went to ACPI / MSDM and took note of it. Could this key be for Windows 7 instead of 8? I never heard of Windows 7 keys in BIOS, but with MS everything is possible.