6x gtx 1070 ethereum Rig shuts down

[Permonik]

Hi guys,
I am just experiencing problem, that my new rig shutting down.
My rig:
2x Msi gtx 1070 Gaming X OC 8gb
2x Msi gtx 1070 QuickSilver OC 8gb
1x Msi gtx 1070 Gaming Z OC 8gb
1x GainWard gtx 1070 GLH Phoenix
6x kolink pci-e riser (powered)
ASUS PRIME Z270-A
Intel Celeron G3900
Patriot Extreme Performance Viper 4 8GB (2x4GB) DDR4 2400
ADATA Ultimate SU700 - 120GB
CoolerMaster MasterWatt Maker, 1200W
Windows 7 64bit ultimate
Claymore dual miner (only ETH mining)

All MSi cards memory speeds are 8400Mhz, cores are -125Mhz and power just 65.
Gainward memory is on stock and core -125Mhz and power 75.

PSU gives me the power consumption around 760W. On the wall it is similar 800W. If there are everything on the stock, the power consumption is around 950W.

And now my problem. Rig is shutting down and I don't know why. Sometimes it happens after 60h of mining, sometimes after 6h. And also it happens me couple of times when I run some program on rig, or I just connect via teamviewer. It seams that 35% of teamviewer connections triggered the crash. 
Temperatures of cpu and mobo are bellow 40degree and GPUs are somewhere between 60-67degree.
PSU has 50degree
So, what will be related to crash? (there is not a BSOD, just shutdown)
THX

[Juggar]

Well what does the log say?

[Permonik]

Hi,
Log say nothing, everything looks fine. Log just ended when rig shut down.

[duboisi]

Once PSU goes over 50c, its efficiency will drop drastically.

[Permonik]

Hmm, temperature of PSU was never bigger than 56degree. And in the internal PSU application I can see that efficiency is maintain around 93% on this temp. Also, two pci-e lines can maintain 100A together. On first is around 37A and on the second is 22A.

[umine]

Have the same problem with the approximatelly same config. Solved with remote control power supply by Mikrotik router (Hard reset on responce absence)