In the Synodical letter from the Council of Constantinople, the bishops give a short summary of the catholic faith:
This is the faith which ought to be sufficient for you, for us, for all who wrest not the word of the true faith; for it is the ancient faith; it is the faith of our baptism; it is the faith that teaches us to believe in the name of the Father, of the Son, and of the Holy Ghost. According to this faith there is one Godhead, Power and Substance of the Father and of the Son and of the Holy Ghost; the dignity being equal, and the majesty being equal in three perfect hypostases, i.e. three perfect persons.
Godhead, Power, and Substance are all “of the Father and of the Son and of the Holy Ghost.” This is as conservative as it gets.
Important for us moderns, however, is to note that the power is one. Often we think of the Father’s power or the Son’s power or the Holy Ghost’s power as if they were individual powers, but the pro-Nicene’s used power as a means of unity, and thus it is really but another name for the divine essence.
We confess the one Power of the Father and of the Son and of the Holy Ghost.
Wedgewords 
This understanding of “one Godhead, Power, and Substance” appears a bit different than what we find in Athanasius. For him, of course, there was one Godhead, etc. but it was distinctly the Father’s, which he shared/gave to the Son and Spirit.
“thus it is really but another name for the divine essence.”
No, because as far as the episteme is concerned ergo —> energeia —> dynamis —-> ousia, dynamis is as far back as we can go.
The names of God for the Pro-Nicenes are on the categorical level, in the episteme, of energeia and not ousia. The relationship between energeia and dynamis is that of active potency and one brought to actualization by a Person. The purpose of the dynamis or will of God is to present ‘objects of will’ to Persons (the divine logoi of the One Logos), the actualization of those logoi are the energeiai of God, and these are the divine names. Some of these logoi are always actualized, as God never began them, God’s knowledge, God’s omnipotence, divinity, simplicity, etc., and some of these logoi are actualized by God as God sees fit (Creation). The logoi are all the rational principles of both deity and humanity (as microcosm of the world).
It is HYPOSTASIS that brings things from active potency to its actualization.
Photios