If I use default its a big difference, dont want to lose hashrate
on default clock 1030 I get cca 6,15 mh/s with temp ~75, on 1155 clock I hit 6,82 mh/s but temp is 88...dont know what should I do...

if you have free electricity - stay within 85C.
if not - measure your rig's watt/mh, at the wall
thanks for the info, this is what I was looking for, since I have free electricity