There are three datacrons on the Republic faction planet Ord Mantell. All three are quite easy to get to and provide minimal attribute bonuses and one matrix shard. All three are required for the Ord Mantell Datacron Master achievement.
The Ord Mantell +2 blue mastery datacron.
Codex type: Achievement: Datacrons
Codex location: Ord Mantell: Savrip Island
Codex coordinates: -656, -575
Faction: Republic
Class: Jedi Consular - Jedi Knight - Smuggler - Trooper
Associated Achievement: Ord Mantell Datacron Master
The Ord Mantell +2 yellow presence datacron.
Codex type: Achievement: Datacrons
Codex location: Ord Mantell
Codex coordinates: -976, 206
Faction: Republic
Class: Jedi Consular - Jedi Knight - Smuggler - Trooper
Associated Achievement: Ord Mantell Datacron Master
The Ord Mantell red matrix shard.
Codex type: Achievement: Datacrons
Codex location: Ord Mantell: Mannett Point
Codex coordinates: 778, 134
Faction: Republic
Class: Jedi Consular - Jedi Knight - Smuggler - Trooper
Associated Achievement: Ord Mantell Datacron Master