you need to find out what the bios command is to activate the boot loader on your machine ????
example; on most asus motherboards you keep tapping F8 at start-up until you see a boot loader menu appear >>>> then you choose hard drive from the boot loader menu >>>>> then a list of all drives in your machine will appear >>>>. choose the drive you want to boot from
in gigabyte boards F12 is the boot loader
Dells I "think" use F1 or F2 ??? dont remember now
you will just need to play around with "F" keys and keep trying till you find the command for the bios boot loader ????
just give us a shout if you need help