what is it called when you play two power chords at the same time? ex:

i remember if you move it to the open string instead of the 5th fret and strum all 6 strings its refered to as Em(add.9th)<-- the 9th being the d string i believe, but is there a name for just these first three notes?
If you're in A major, that would represent an Aadd9; if you're in A minor, Amadd9.

By itself it's A5add9.
According to the Guitar Pro chord thing, it can be called Asus2, Esus4, E/A (no 3), Bsus4/A (no 5), or B7sus4 (no 5).
I'd say Asus2.
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A5add9, really..
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I just learn the formula, apply it to a key, and use said notes on fretboard. Why? Cuz I'm not a pussy.