Are you running them in the right configuration? A2, B2, C2 dimm slots? Only way to get triple-channel if you got 4GB x 3 sticks. I've also read if they are seated in other configurations, it can cause this issue or even sometimes resolve it. So you'll have to play musical slots for a while until you hit the sweet spot.
Are you running on a X64 OS?
You didn't give much to play off, so it had to be asked...
It could be possible, that your CPU needs to be reseated (apparently a huge issue with X58's) or your BIOS is set to "Auto" for memory which apparently for your board, can give insufficient voltages to your sticks. Also what brand of RAM are you using? People have reported more success with Corsair 4GB x 3 Kit instead of GSkill.
Hope something works..