what unlinked settings are you using?

for some reason i found that anything with 8x appears to be much stronger than unlinked settings with 9x.

i.e. 8 x 450 is much better than 9 x 400.

i also use the gskill 8000hz's.

edit: one thing you might want to try is loosening up the subtimings a bit. the ones that are programed (at least with the 8000's) are pretty tight even for stock.