Open Chords to Power Chords.

The E barre would be up one fret to the 7th(not 6th, 6th fret is D#/Eb) fret in a D form barre.

And to answer your question regarding minor chords in barre chord shapes as long as the differentiating string is not played( example; Bm X24432 and B X24442/ the differentiating string is the G string , 3rd fret on the Bm 4th fret on the B major) the first 2(A shape), or 3(E shape)(from your chin to your knee) strings of the "power chord" will work with a major and/or a minor chord progression.

A shape barre chord; X02XXX or X022XX, x24XXX or X244XX, etc...
E shape barre chord; 02XXXX  or 022XXX, 24XXXX or 244XXX, etc...

A "Power chord" is really just an interval of a perfect 5th.  You can take that shape anywhere down the neck, or across it to the B string, and you're playing a "power chord."

ummm... sortal

Right.  I'll get that right some day.

If you're playing the b string, it's no longer an interval of a perfect 5th.    "Power chords" aren't chords at all.  They're just intervals, so *any* shape that provides that interval will work for you.

Those aren't power chords.    That's just a closed D shape, giving you a proper major chord.   A power chord is *just* the interval.

Just curious, when did the term "power chord" come into being? my early recollections of the word "power" was associated with the early "hard" rock sounds of groups like deep purple,zeppelin,Hendrix ect.. what gives this form the "power" over any D or A shaped bar position?

Thanks Toney, I remember Link Ray and the Raymen when Rumble first came out he used a tremelo effect on rumble I cant remember how many times I played this song at sock hops and cyo dances when I was a young upstart dude now im an old upstart

The reason it sounds as "powerful" (partial pun intended) as it does is because of the overtone series which creates the third in a way which is more detailed than i care to explain, but suffice it to say that the third is there, but not in the traditional sense that would be associated with in chords.

Maybe I could answer that one. I have studied the physics of sound and can concur with flatliner.
A vibrating string, for example the low E string, will sound its fundamental frequency, the E, by vibrating along its whole length. (Say 25 inches for the sake of example). However, the string also vibrates in other "modes" such that it appears to vibrate along half its length, third its length, quarter its length, fifth its length and so on. These are called higher harmonics or overtones*. Each higher "harmonic" (or overtone) is weaker than the previous. So you tend to hear the lowest (fundamental) tone and the presence or absence of the higher harmonics colours the sound you hear. For example, playing near the bridge encourages higher harmonics and consequently colours the tone of the note.
Now the tricky bit. The harmonics create notes which relate to the fundamental (lowest tone) in a mathematical sequence. The 2nd harmonic (where the string vibrates along half its length) is twice the frequency of the fundamental. This creates a note an octave higher than the fundamental. This note sounds with the fundamental and colours the tone. The next harmonic (string vibrates in 3rds) produces a note 3 times the frequency of the fundamental, and is an octave plus a fifth (13 notes) above the fundamental. So if the fundamental was a C, the 2nd harmonic is C above that and the 3rd is the G above that. It goes on. The next harmonic produces the octave above that, and the 5th produces the third of the chord (the E) above that.

Guitarists can force these harmonics to sound by touching a finger on the vibrating string.
If you touch at the 12th fret you force the string to vibrate in two halves, producing the 2nd harmonic, an octave above the fundamental. If you touch the string at the 4th fret you force the 5th harmonic, which is the 3rd of the chord. (On the bottom E string you would get a G#)
If your guitar string is is 25 inches long, the 5th harmonic (the 3rd of the chord) is encouraged by playing or strumming about 7 or 8 inches from the bridge. On my acoustics, this is just above the sound hole. Plucking the E string hard here, and listening, one can hear the 3rd of the chord (the G#) sounding quite clearly.
The same applies to electrics.
Hope this helps.
* There is a lot of confusion and disagreement over the meaning of the words overtone and harmonic. I have used the convention where the lowest note (fundamental) is also called the 1st harmonic. The 2nd harmonic, the octave above, is referred to as the 1st overtone, and so on.