HDMI settings

[Hextejas]

I did a fresh install of ver 1.05a and got nothing but a black screen
So, I modified config.txt to be:

Hdmi_safe=1

Now it's running, but the picture occupies the middle of the screen with giant, wide, black bars on the right and left.
So, what other HDMI settings should I use to get a full HD screen ?

Thanks