Fallout
The first "Fallout" game features T-51b powered infantry armor, often just "power armor," and an advanced form called hardened power armor. Powered armor dates from before the war, and players can only find it in the Brotherhood of Steel headquarters in Lost Hills. Ordinary power armor provides a 25 AC bonus, 40 percent damage resistance against plasma, electricity and normal damage, 50 percent explosion resistance against explosions, 60 percent against fire, 80 percent against lasers and 500 percent against EMP blasts. It increases strength by 3 points and radiation resistance by 30 points. If you have a suit of power armor and a set of Chemistry Journals, Miles in the Boneyard will harden it, increasing most resistances by 10 percent to 20 percent.
Fallout 2
"Fallout 2" includes basic power armor and hardened power armor, as well as advanced power armor and advanced power armor Mk II. Basic and hardened power armor work the way they did in the original "Fallout" game. You can find power armor in a Brotherhood outpost in San Francisco, a locker in the armory of the Mariposa Military Base and in the Enclave oil rig. To get hardened power armor, pay Crocket in San Francisco $10,000. Advanced power armor has an AC bonus of 30 and increased resistances. It appears in a locker in subterranean Navarro. Enclave forces exclusively use advanced Mk II power armor, which offers an AC bonus of 35 and weighs less than advanced armor. You can find this armor in the Oil Rig, in a small alcove to the right of the puzzle room.
Fallout Tactics
"Fallout Tactics" features slightly different powered armor. The Midwestern Brotherhood and Eastern Brotherhood armor that appears in the game is called "power armor" and "advanced power armor," but it has little in common with the armor from the first two games. Midwestern Brotherhood armor provides an AC bonus of 30, electricity damage resistance at 10 percent, gas resistance at 30 percent, explosion and energy resistance at 50 percent, normal resistance of 55 percent and fire resistance at 60 percent. It also improves strength by 3, poison resistance by 15 percent and radiation resistance by 30 percent, but makes several skills harder to perform. Brotherhood members can buy this armor for $19,500. Advanced power armor improves resistances and strength. Players can find this armor in a hidden room in the Newton Reaver base or buy it in the Bunkers after Canyon City.
Fallout 3
"Fallout 3" offers several power armor variants. These include the T-45d power armor, an early version that provides 40 damage resistance and increases strength and radiation resistance while lowering agility. Capital Wasteland merchants sell this armor. You can also get it from Sarah Lyons or the corpses of Lyon's Pride members, from Brotherhood of Steel corpses, or from Outcasts. "Fallout 3" winterized T-51b power armor superficially resembles armor from the first two games, but has a DR of 50 and +25 radiation resistance. Players acquire this armor during the "You Gotta Shoot 'Em in the Head" quest in Fort Constantine. The game also offers Enclave power armor, and Tesla armor, which boosts energy weapons skills. Enclave Hellfire armor, added via the Broken Steel add-on, works like T-51b power armor and improves heat resistance.
Fallout: New Vegas
T-51b power armor in "Fallout: New Vegas" comes in normal and Brotherhood variants. Both offer a damage threshold of 25, an extra 25 radiation resistance and 1 additional point of strength. Brotherhood armor also acts as a disguise. Players can buy ordinary power armor in the armory, find it on a dead prospector at Deathclaw Promontory or in the Brotherhood Safehouse after patching the game. Brotherhood armor appears only on Brotherhood of Steel members. T-45d power armor, also available in normal and Brotherhood variants, offers a 22 DT, extra 10 percent radiation resistance and reduced agility but more strength. Remnants power armor provides 28 DT and extra 15 radiation resistance, while Remnants Tesla armor has a DT of 25, extra 20 radiation resistance and adds 10 to energy weapons. NCR salvaged power armor is a T-45d variant with reduced DT that works as a disguise in the New California Republic and doesn't require training to wear.