...
one question though, why aren't the risers powered?

If the cards are powered by 6/8 pin plugs and aren't strictly powered by the pcie connector, there shouldn't be a need for the risers to be powered. Seems to be the case here.
I wasn't aware of that, you learn something new every day! thanks

Hi, the risers aren´t powered because when I finished the assembly I took the photos, and then I connected it to the power.
Regards.
Hows the heat dissipation? I'd expect it to get quite warm as all the heats going into the center