Thanks for links.

You bet..
If you get a second, i posted a while back about an issue I'm having in 0017 where one card runs at 66% capacity while the others are at 100%. I'm just wondering if that's something you've seen before, and if there might be a straight forward solution to it. If not, I'll probably just wait until I swap boards in a few days to mess with it since otherwise it's running solid as a rock with all 6 gpus.
Is the hashrate lower with the GPU running at 66%?
Hey FZ - just wanted to let you know I resolved the issue with my underpowered GPU... turns out having 2 risers on one SATA power line is frowned upon... once I put all the GPUs on their own lines the system is back up at 100%
With 1080 or 1080ti that is best; especially if they are AM models. I haven't heard of anyone needing to do this with 1070s or 1060s; what type of GPUs are you using?
I've got:
2x asus dual 1070
3x EVGA superclock 1070
1x Nvidia 1070 FE in the x16 slot
Asrock z270 Killer SLI/AC mobo (no external power to mobo for pcie (no option for it))
dual 750w PSUs - 1x evga and 1x thermaltake
64gb USB 3 stick
No 1080s in this rig atm, though I had a 1080 ti in there yesterday in the x16 slot so no riser but the problems I've had arose with all 1070s
Before, I had it setup so that:
2 risers were powered on one molex power line
2 riser on 1 SATA lines
3x 1070 each on its own power line (450w); and
mobo/cpu all on the EVGA 750w psu; [all of that should be well within the acceptable range of draw from the PSU]
Then the other 3 1070 GPUs and 1 riser on molex were powered by the 750w thermaltake [again, well within the total power load taking overhead into account]
New setup splits the risers between the PSUs 2 go to separate lines on the EVGA, the other 3 on separate lines on the thermaltake, all on SATA power cables except 1 (though that shouldn't make a difference), and the risers are powered by the same PSU as the GPU main power is coming from whereas before they weren't.
the mobo/cpu are still on the primary EVGA PSU, and the thermaltake is connected by a Y splitter ATX cable.
The result is that the more even power load resolved the problem, though I can't be absolutely certain it was solved by splitting the risers to different lines exclusively.