Yep, That's the one. Thanks for the heat dissapation link.
The led strip is driving 180 mAmps per channel at max and it is rarely reached. There's max 5 channels per chip. So 0,9 amps is the max.
How would I explain the flickering. It is some (high frequency) changes in the intensity of the light. So that light is not stable and calm and steady. It is actually doing it really little, but enough to catch the eye.
I need to do some testing without serial reading.