Having a problem accessing BIOS or UEFI Firmware Settings Menu. Using a Z170X Gaming 3 MB with i5 6600K CPU which should be compatible with Win 11 but PC Health check says CPU is not supported but it is, so I think settings in UEFI need changing. The mb manual says the 'Del' key on startup should enable boot into BIOS but can't get that to work. Have ensured that 'Fast Booting' is not enabled but still never see any flash screen. I went into Win 10 Settings> Recovery>restart>Advanced Settings>UEFI Firmware Settings>Restart and screen goes blank but nothing appears. Computer is connected to dual monitors. Don't know what else I can try.