My pi is connected to a 2A power supply and the led strip to a separate 2A supply.
I think I explain the situation above wrong. Not the led strip is flicking but the tv.
I also have the rainbow square on my screen (i know that is not enough power for the pi) but why didn't did it before.
I just reinstall on a brand new sd card the OpenElec and hyperion and is happening again. When Hyperion is stop there is no problem. When I swich it on the pi is stuck (black screen) and i need to remove the power.