Probably the settings.
like always ISO 100
Sounds like the problem, good exposed iso 100 gives almost no noise, but underexposed iso 100 gives much noise.
Try to enable raw histogram in magic lantern menu and see how it looks ? (if you're unsure how histogram works, try googling it).
You want the histogram to touch the right side, then you're exposure is good.
It's better to go higher in iso to move the histogram to touch it the rights side, so use iso 200, 400, 800 maybe even 1600 if nessecarry.
It's always better, noisewise, to use higher iso to get proper exposure, then using low iso and have underexposure.