No, either or. You don't have to run the backpane at all, its probably easier just to wire the blades directly.
It works with power in booth ends. How is it harmful? It might be worth it compared to building something else to make them stand...
Unfortunately I only got the green 4-pin adapters for 2 of the blades or I would run then without power in the backplane yes.
Ok nevermind again, I think the problem is drawing two much power on 2 PCI-e outlets in the PSU. (They have 2 connectors each) I used a third PCI-e module and now it can power everything with backplane only.
Thank you for the guide and the help.
Now all that remains is to get the PSU to run without a MB. But in worst case I will just go find a old MB in the garbage room and jumper the power on it I guess ...
PS.
I did contact the manufacturer of the PSU. They refuse to give support on "inappropriate use" of the PSU of course but they did hint something about not starting if there isn't a "realistic" load on the PSU. I think this PSU is just to expensive to be fooled by only having a load on the 12V slots?