@Humbleminer: thanks, that's exactly what it was!! Now finally mining away with all 6 gpus for the first time!! Epic!

2 things though:
- vddc shows 1.2v in the web stats interface but max 1.14 in my conf file... And ccc seems to confirm max at 1.14.
- hashrate is 15kh lower per card than in Win8.1