Hey man for ur gigabyte motherboard ( GA-P35-DQ6)
there are two ways of doing it(bios update)

1- u can use gigabytes @bios which is an app that comes with your mobo cd.
@bios automatically detects your mobo ver and bios ver and lets you download the
latest bios from the gigabyte website. After thats done u can flash your rom and write the new bios on to it.

2- or you can manually go to the gigabyte website click on motherboards specify your model NO: and download the latest ver of bios(it should be .bin file ext). Once that is done copy it into a floppy or usb pendrive.
upon next boot enter "q flash" mode by pressing the the respective key(del/end/home/f12) . "Qflash" will walk you through it


* Remember to backup your bios first before u flash ur rom. Do it at ur own risk!

I suggest u use @bios. I used it it worked fine for me...................