I don't know if anybody is interested in this topic anymore but I felt obligated to inform it in here about what happened in my situation;


As suspected, apperantly my problem was with the psu I was using(Xilence Redwing 800W)

I replaced my psu with Cooler Master Silent Pro Hybrid 1050W.

2 Asus R9 280X Tops are doing great with it.

Thanks for the help.