Windows – Enabling UEFI mode in BIOS after having set it to CSM mode, and not being able to get back into BIOS

bootuefiwindows 8

I set my BIOS to CSM only mode after being unable to boot into windows after upgrading it to 8.1 and not being able to boot from a USB stick to repair it.

I ended up putting in a formatted SSD, and managed to install windows 8 again from a USB stick. Only problem is I choose Windows 8 Pro instead of Windows 8, and so my key wasn't valid.

It's a Samsung series 9 laptop (NP900X4D), it tells me to press F2 for setup during boot, but no matter how many times I press F2 or any other key (F10, F12, DEL, etc) during the Fast boot , it doesn't show the the setup (BIOS) screen.

I don't get the option either when I use the windows Advanced Boot Options screen, I no longer have the option to boot from a USB drive, or to boot into the UEFI BIOS settings. I cannot even boot from a USB stick before windows loads up.

So I was wondering if there is a way for me to change the BIOS back to UEFI mode from CSM, without going through the BIOS, or if there is some other program that would let me load up the BIOS through some sort of USB tool I could boot from if I took out the SSD.

EDIT: Managed to get it working after installing an updated firmware for the motherboard from the Samsung site. The version that shipped wasn't responding to key strokes to allow me to enter the BIOS/UEFI.

Best Answer

You may consider trying to do a completely fresh install with a different windows disk. Windows really like to mess around in the BIOS during installation, and if you can get it running, you can try to:

  1. Change the Bootup options from within windows, possibly by using bcdboot.exe.
  2. Restarting the PC by holding down [Shift] while selecting and clicking on the Restart option on the power-down menu. Your PC will restart into "rescue mode" and you will presented with a Windows boot menu, choose Troubleshoot >> Advanced options and then UEFI Firmware Settings.
  3. Update the BIOS by downloading it from Samsung support site, and flashing it, if available.
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