I'm looking for black metal bands that utilize the simple, uncomplicated keyboards like in Dimmu's For All Tid and Enthroned's Prophecies of Pagan Fire. Not over the top symphonic stuff, but more atmospheric.

Thanks.

Try Sear Bliss, especially the earlier works, and maybe Covenant (nor) "In Times Before The Light".

Mörker kind of has that early Dimmu Borgir sound. Try their album "Höstmakter". It kind of has the same vibe, but not a complete clone.

Quite a bunch of Norwegian bands from the same period are applicable, with mystic and slightly understated keyboards giving a particularly ghostly vibe. Below are some of the more applicable albums I can think of:

Gehenna - Black Seared Heart, First Spell, Seen Through the Veils of Darkness, Malice

Covenant - In Times Before the Light

Troll - Drep de Kristne

Satyricon - Dark Medieval Times, the Shadowthrone

Ragnarok - Nattferd, Arising Realm

Manes - Svarte Skoger

Morgul - Parody of the Mass

Here are some albums from bands of other scenes that capture some of the same atmospheric essence of earliest Dimmu Borgir, though of course not necessarily in a completely similar manner:

Sapfhier - Trollskogen, Under Eternally Grey Skies

Behemoth - From the Pagan Vastlands, Sventevith

Kermania - Ahnenwerk

Bann - Antiocha

Throndt / Idhafels - Split album

Infernum - Taur-nu-Fuin, Farewell

Khors - Mysticism

Lycanthropy - As the Mourners Arise

Aetheres - £aknienie Misterium Nocy