Currently I have 5 x MSI-R9-390 rig, doing around 145Mhs or 29.xx Mhs per card.
Afterburner settings at -100mV, 1015mhz and 1500mhz, core voltage, core clock and memory clock respectively.
The EVGA 1600w G2/Gold is pushing around 1270w to 1350w for the system ASrock H81-BTC, Celeron 1840 and 8GB RAM.
Initial plan was to use only 5 x GPU so that I can avoid using 2 x PSUs.
However, with the 1600 EVGA and undervolt settings, could I do the 6th card at 1450w (within the safe zone of 15-20%) of the PSU.
It will be prefered not to get the PSU worn out quickly if the rig pushes the wattage to maximum because even EVGA Gold is only about 90% efficiency.
Any advice to get the 6th card in without fear of the burning out the PSU?
Thanks
limit the power used by each card, downclock them a bit, you probably might fit them all in the 1600w, by losing some hash, the ratio should be the same in the end
I am experimenting on the underclocking for these 390s, and it may just go under 1600w but I was advised by fellow riggers that 1600-G2 on continuous power is only 90%-92% efficient, so pushing it too close to max will shorten PSU life.
you have one rail so zero issue on that balance rails comment.
the psu can give 1600 watts dc which is about 1800 watts at the plug.
a long review on it:
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=391this shows it under a 1595 watt dc load which was 1792 watt ac at the wall
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story4&reid=391I believe you can do it but your wall plug if 120 volts needs to be a 20 amp dedicated circuit to do it longterm.
Thanks Philip for the guide.
My country uses 240v and I have 60amps to play with, any impact based on the above parameters on 220-240v specs?
sure 60 x .8 = 48 amps at 220 volts = 10560 watts on the low side 48 amps at 240 volts = 11520 watts on the high side.
as your 60 amp max must be derated to 80% for safe 24/7/365 operation.
so I do not know how your 60 amps are distributed but you can use 48 amps of it safely if set up correctly.
your 1600 watt psu doing the max at 1800 on the wall
is 1800/220 = 8.1818 amps
or 1800/240 = 7.5000 amps
I would say think of it as 8.25 amps of the 48 you can do
So I would want a 10 amp circuit on the 60 amp you have
Actually six 10 amp circuits for you sixty amps and stay under 8.3 amps on each one
thanks again Philip - I see it clearly now. My electrician had infact suggested zoning the 60amps (63amps to be exact) into 2 zones so that it won't trip the other if anything bad happens.
according to kill-o-watt meter, each 1600 PSU (EVGA 1600w Gold 80, 90 efficiency) draws 1270-1350w and hovers around 5.46-5.55 amps.
this is using settings of -94Mv (undervolt core), 1015mhz (GPU) and 1500mhz (memory) = delivering 29.xx MHs per card - I am happy with this speed.
I understand that underclocking the memory has no impact to overall voltage reduction, that's why I kept it at 1500mhz stock.
! That's true that they're pushing it too far. I might finally order some older cards, or maybe even a 1070. 
will follow this thread for sure. 
