I have a simple question concerning Grub. When Ubuntu it's the only system installed on a machine, Grub doesn't appear when the computer it's turned on, my question is: When Ubuntu is the only system, Grub it's not installed on MBR?

I has this doubt when I tried the ASPM command in Grub, to see if it could save some battery on my notebook, and the difference was only 0.4W. I don't even know if it made some effect or it's just a normal oscilation.

Thanks.