Recognize GRUB on bootable USB Hard Disk when Power on

[nb123]

Just to let others having similar problems as me know what I've done prior to this point, I've installed 2 Linux distros on an external USB hard disk, and put the GRUB on that hard disk as well. I'm very close to getting the GRUB to boot both distros correctly. However, I've another problem.

When I power on my system and press F12, it doesn't instantly give me an option to boot from USB hard disk. I must kinda do some sort of a cheat in order to get this option. 2 ways I know of doing this are starting Windows and then restarting the computer through windows, this works. Also, if I run diagnostic tests and then escape it halfway, then restart the computer, I also manage to get a boot from USB hard disk option. How do I make my BIOS recognize the GRUB on my USB external hard disk?? Do I have to install a GRUB on my primary hard disk? I'm trying not to interfere with Window's bootloader... If possible, is there a way to activate certain devices at boot to recognize the USB hard disk booting device? I don't really know how to search for answers to this online...

[devils casper]

Set USB Drive as First Boot Device in BIOS.

[nb123]

Thanks! worked like a charm, I was worried that it may cause it to load GRUB when my USB was connected even though I wanted to run windows but it didn't, it bypassed it unless I pressed F12 to select USB hard disk manually. For others out there, don't worry if the BIOS seems to be loading slowly, it'll work.

[devils casper]

Glad to help you.