Okay I'm just supid. I traced the wrong power cord... it wasn't even hooked on to the psu.
But it still don't works. And I am not entirely sure if I connected it right.
The power cord that goes away from the HDD looks like this: http://compare.ebay.de/like/300590431998?var=lv<yp=AllFixedPriceItemTypes&var=sbar
I connected the middle one to the opposite from the psu. Should i connect the second one two?