Rakata Energy Cube

They are used in the devices Drosmier mentioned to gain access to a datacron. You need to use all four terminals, meaning you need 4 cubes, in order to get to the datacron.

The datacron grants a Green Matrix Shard.

Found two in The Tomb, on Belsavis:
-436, -2179
-379, -2482

Found one in High Security Section, on Belsavis:
-1219, 1348

Once you have used the Datacron that requires the Rakata Energy Cubes, you can no longer pick up the Energy Cubes.

As far as rakata energy cubes collecting goes use this YouTube video. http://www.youtube.com/watch?v=DN0cn6ylrgQ&context=C3068b66ADOEgsToPDskJ9yYDcKiTGnfzAeqweOk0W

I would like it know I just watched it and all credit goes to the guy who made it so give him some love as this video was a life saver. I had none and got all four watching the video and following his path one and half times.

I made a picture of the cordinates given by Yanagi:
< Link > Hope its usefull.

I found Rakata Energy Cube's at 7 of the 8 places when I went to get them (got 8 in total over 10-15min), and they apear to spwan randomly a few min after you have taken one(Only one will be ut at the time).

Before you obtain the associated datacron (which is for a green matrix shard & galactic history 71) you can pick up an unlimited number of energy cubes, in stacks of 4.

As for their spawning time, I got 5 at the same location at the northern region back to back with a 30s spawn time inbetween, and then couldn't find any in either region for another half hour.

They are tradeable, vendorable, and mailable, but not AHable.

Like someone else said, once you do pick up the datacron, you can't interact with the cubes anymore (though any remainder stay in your inventory)

I’ve gathered several screenshots of my gathering the Rakata Energy Cubes here: http://odoshi.net/belsavis_datacron/ over the course of an hour (16 cubes in one hour, solo).

These screenshots are taken in consecutive order (the order they spawned – just in case there is a pattern). They stack up to 4, and you can have more than 4 (I picked up 16). They can be traded as well.

Locations:
-382, -2480 (4x)
169, -2097 (3x)
-737, -1789
-247, -2307 (2x)
-482, -1614 (2x)
-703, -1963
-437, -2180 (2x)
-158, -2010

found on at -763 , 272

on the way to the willpower datacron, in the small "passage" starts at -830, 789. (High security section)

It seems that multiple people can grab the datacron unlocked by the Energy Cubes while it is active. I collected my four energy cubes and went to get the datacron, and two other people were already standing in front of it. The machine was disabled on its cooldown, and I was able to grab the datacron. Neither of the other two people said anything, both appeared to interact with it and zone out. I waited by the machine after apologizing and saying I'll re-unlock it or trade the cubes, but got no response.

While it's possible that I stole the datacron from them, it seems more likely that it can be accessed by multiple people while it's active. I still have all four energy cubes and the codex entry.

I was not able to confirm whether energy cubes from multiple people can be used to unlock the datacron, but it may be possible to team up with someone else to access the datacron.

So I found one of these in Belsavis up in one of the last zones for the planet.

Coord's:
50,-2052
-1253,179

I have no clue what I'm supposed do with it...I assume I'm supposed to take it to some place and use something to "harness the energy" but I'm clueless at this point.

Just found one at exactly -483, -1613
next to two giant plants. Then I went afk for about two minutes and when I returned, the cube had respawned at the same position!
Unfortunately this didn't work a second time.
Edit: Just found another one at 170, -2096
(coords could be off by about 2 points, picked it up, ran around a bit and didn't remember to note the exakt location. It was on the west side of a foot of a hill with giant roots on top)
Edit 2: And found the fourth one at exactly -704, -1962
near three giant plants.

To recap: Found all my 4 cubes within about an hour on these 3 locations:
-483, -1613
170, -2096
-704, -1962
These three locations were all mentioned in the second post of this thread: http://www.swtor.com/community/showthread.php?t=113717. This post mentions a fourth location I did not need to visit now. Maybe it helps others.
On page 8 of this thread two people posted a video of a route around the possible spawn points and a map of those points. I won't link them as to not take the credit for this.