I was watching one of justin sandercoe's videos on youtube explaining how to play powerchords and he recommends muting the string not played. For example, in a 3 note power chord, he demonstrated how to mute the strings that were not being played. That way, only the notes in the power chord are heard. Anyway, how many of you guys actually use this technique? I've been playing around with powerchords for a while and didn't bother trying to mute them until I saw Justin's video. I'm sure that he demonstrates the proper way but I just can't get used to playing the power chords in that manner. Any suggestions? Thanks
Well, I've been using my thumb to mute the low E string when playing a chord since the day I started playing.

And if you're playing, say, the second fret of the A string and the 4th fret of the G string you need to have the finger on the G string touching the D string ever so slightly so that it doesn't ring when you strum.
Only if you really like to get into your music (Or like to show off) you should use this. Also if you're a messy player, but other then that you should have enough pick control to hit only those 2 or 3 strings and come back up without hitting a different string.

As for me, I do it sometimes. In drop D I do it because getting a nice attack is always good in metal ^_^. As for Standard, I tend to be more clean so I don't worry about it much.
I do, not all the strings, mostly the low E.

But thats just because I play really hard, when learning a song I always play it "properly" first, lol.
On the power chords just let your left hand mute the strings below them and like those above said, use your thumb to mute the E or even both E and A. With the left hand it's not too hard to get used to just resting your finger over those other strings. And not your free fingers, just the one that's playing the higher note(s) will suffice. You'll get it, and after a bit you won't even think about it. You'll just do it.
Unless you have terrible pick control you would never need to do that, you should just be able to attack the three strings in the chord without any others sounding.