From an article I wrote some time ago.

"A usual distinction is made between American Power Metal, known by the acronym USPM, and European Power Metal. USPM sounds grittier and slightly slower than its European counterpart that features cheerful melodies and prominent double-kick drumming.

Proto Power Metal and early Power Metal albums:
Rainbow: 'Ritchie Blackmore's Rainbow', 'Rising', 'Long Live Rock 'N' Roll'
Dio: 'Holy Diver', 'The Last In Line'
Omen: 'Battle Cry'
Warlord: 'And The Cannons Of Destruction Have Begun…'
Queensryche: 'The Warning'
Jag Panzer: 'Ample Destruction'
Manowar: 'Hail To England'
Helloween: 'Walls Of Jericho'

Recommended albums to start:
Yngwie J. Malmsteen's Rising Force ‎– 1985 Marching Out
Helloween ‎– 1987/8 Keeper Of The Seven Keys Parts I & II
Savatage - 1987 Hall Of The Mountain King
Riot - 1988 ThunderSteel
Running Wild ‎– 1988 Port Royal
Crimson Glory - 1988 Transcendence
Rage - 1989 Secrets In A Weird World
Viper - 1989 Theatre Of Fate
Heavens Gate - 1991 Livin' In Hysteria
Angra - 1993 Angels Cry"