absolutely same result with the brick

all 4 together they just won't run stable (or 3)

but with 2 or less at the same time I am great

EDIT: no sure if it might help to diagnose, I tried running all 4 stick at freq 75

so by the formula 75 x 0.228 = 17.1 Gh/s

same behaviour, the first two sticks I start run perfectly at 17 or even a little more

as soon as I start the third and/or forth boom, they all start jumping up and down, even dropping to 1 Gh/s and then trying to go back up, with WU % around 50 % or less