I've heard about this issue before recently, but I'm not sure what the fix was (big help, right?)
Do you have a wireless keyboard? If so, they can be slow to "wake up", so your board never receives the Del/F2 input. Try a wired keyboard.
Does your board have an external CMOS/BIOS reset button? If so, try this: Press it, which will clear all the values in the the UEFI, but forces you to enter the UEFI to at least select default values. Once in the UEFI, try to find settings that will slow the boot down. My ASR Z77 board has a Fast Boot option, which you may have set to Super Fast. Set it to the slowest value, and see how it goes, and adjust from there if necessary. It sounds like you have only one or two drives, and the OS is on a SSD, correct? More devices slow down POST time, and give you a chance to get into the UEFI.
Actually, no system specs entered, forum rules, the end for now.