I'm trying to downgrade a Toshiba Satellite C55T-A5123 that came with Windows 8.1 on it to Windows 7 x64 bit. I'm stuck at not being able to get it to boot the installation media. I've turned off secure boot and tried both from a DVD and from a USB flash drive.
I've verified another PC will successfully boot both the DVD and USB flash drive, so I know they are not the problem. When I turn on the laptop, I'm hitting F12 to get the boot selection menu and after I select the DVD or USB flash drive option, it just goes on and boots from the hard drive into Windows 8.1. I've even tried changing the boot order in the BIOS/UEFI setup. I also read one suggestion about going into the BIOS/UEFI setup and changing the boot mode from UEFI to CSM, but that option is nowhere to be found.
Also worth mentioning I am making sure that Windows 8.1 is completely shutting down by using the Shift key method. I've even resorted to pulling the plug and battery to make sure.
Also worth mentioning I've verified the DVD drive and USB thumb drive are visible once the laptop boots into Windows 8.1. So, I know that's not the problem either.
I've installed every version of Windows from MS-DOS to Windows 7 and dozens of GNU/Linux distributions so many times in my life I cannot even count them. I've even installed Gentoo for crying out loud and I've never had this much trouble getting the install media to boot.
Any suggestions?
Best Answer
Do you have legacy boot enabled? If not first try to enable it and try booting from your CD/USB again.
If that doesn't work, this might be a problem with the BIOS it self. What is your current BIOS version? Is it below 1.30? If it is, I suggest the first thing you try is to upgrade your BIOS by downloading the latest version here. I doubt you have the latest version since the website claims it was posted 3 days ago (4/2/2014) The website I linked contains both instructions on how to flash the BIOS and the download. I read through the instructions and seems like your BIOS should have CSM Mode from this statement in the website.
Go to the Advanced tab, enter "System Configuration" and set the Boot Mode to "CSM Boot."But then again it might not because in the change history for the latest version it states:
Try that and let me know how it goes.