Although power chords can be heard in many styles of music, a sure fire place to hear a slew of them is on modern rock radio. Bands are constantly crunching them out and combining them with muted rhythm slashes and quick chord runs. The following example sounds a bit like the Foo Fighters covering a Bob Mould song, but I think it will illustrate a few cool points.
First of all, I know the chord in measure one looks nothing like the compact root, fifth and root octave combonation that you were working with in the previous example, but looks can be deceiving. The only notes being played here are E and B. Because you are fingering the chord on the seventh fret of the fifth string (E), the ninth fret of the fourth string (B) and the ninth fret of the third string (E), you're simply adding a but more octane to the power chord by allowing the open sixth, second and first strings in on the act. Hey, why not...?
The rhythm slashes in the second measure are there to break up the monotonous drone of the previous eighth note passage. I've chosen to mute all of the strings at the twelfth fret, but you can do it wherever it's most comfortable for you. The chord run at the end of measure four may seem a little irritating at first, but it's there to break up the admittedly square feeling of the passage and to help you get the feel for moving power chords around quickly. If you don't like it you can replace it with some other moving power chord run. You won't hurt my feelings, I promise. It's time to play.