Cheers for the ideas, guys.
Over here XFX warranty is two years, but np with fair refunding, btw. Diamand AFAIK does not appear on the German market at all.
Interesting thought as my cases extremely support out-taking reference designs (np in handling 5970 + 295 due to outtake flow). However, 2x 570 custom design also worked well, though the middle one takes significantly more heat, the CPU too. It also depends how much air the design gets out, I think there are strong differences. Gigabyte seems to take at least some out.
Wish there was one in my flat.
But I can sleep next to a rig running POEM.