I took this from Gilrock's post about his mega tree, because I have the same issue with my fairylights. I the strings are 145 pixels, with power from both ends and to the centre. After talking to a few people I have ensured that each injection point is not shared. But I am still having a flickering issue, except for one string! It is the farthest from the power supply and has no middle injection point, and shares its end injection with the string next to it! I have ensured now that I am not overloading the board or the power supply, does anybody have any ideas?