Fallout 4 – Overseer’s Guardian Damage: One Bullet or Both?

The displayed damage is the regular damage. Power attacks do extra.

The Nukapedia page on Melee Damage states that

• Melee and Unarmed attacks in V.A.T.S. do twice as much normal damage, but this doubling is done before Strength is added.
• Power attacks in real-time combat also double normal damage.

The damage was doubled in previous Fallout games, but the Damage Resistance page says that, for close combat damage in Fallout 4,

PowerAttackMulti = 1.5

So it's possible the multiplier may have changed. Regardless of the multiplier, power attacks do more damage, rather than normal attacks doing less.

Well, as it turns out, when entering Power Armour, your strength is SET to 10. I.e. Power Armour gives you maximum strength, affecting carrying capacity as normal. Therefore by having 10 strength you do not benefit from that particular Power Armour bonus.

As a side note - it should be noted that if you have pocketed armour, which increases your carry weight, you do not benefit from that when IN power armour. In other words, if you rely on greater carrying capacity from Power Armour you should consider these points.