power cords are triads that omit the 3rd. so we get the 1st & the 5th or inverted the 5th and the 1st. Or maybe >1-1-5 > or 5-1-5 > 5-5-1. The use of the 1st and 5th definatly sound strong, also when using distortion we can crank it up. They also lend themselves to a lot of freedom when playin a solo. :)