Out of ideas, need help

I cannot get my head around the following issue, really need help with this;

I have been building R9 390 and RX 470 rigs for my clients without problem, now i got problems with my build, it just wont run longer then 7 minutes.

I already build several RX 470 systems all the same components and brands with the following setup, and already replaced all the componants, it doenst even run for more then few minutes on stock settings.

Have 2 new builds both wont run,

My specifications;

- Asrock H81 Pro BTC
- G1840 processor
- 4GB DDR3 Ram
- 1000W Gold power supply
- 6x MSI RX 470 8GB Gaming
- 3x normal risers, 3x usb powered
- Windows 10
- AMD 16.9.1 drivers
- Dual miner 7 beta

Settings
- PCI to Gen 1 in bios
- Cclock 1050 @ 880mv
- Mclock 1750 @ 850mv
- Windows update off
- Windows defender off
- Task planner all off
- Windows firewall off
- User settings lowest
- Windows running on best performance
- 16GB memory

My bat file ;
[code]
timeout 30

set executable=EthDcrMiner64.exe
set commandline= -epool eu1.ethermine.org:4444 -ewal xx.miner1 -epsw x -etha 0 -gser 2 -mode 1 -r 0 -cclock 1050 -mclock 1750 -cvddc 880 -mvddc 850 -dbg -1 -wd 1

setx GPU_FORCE_64BIT_PTR 0
setx GPU_MAX_HEAP_SIZE 100
setx GPU_USE_SYNC_OBJECTS 1
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_SINGLE_ALLOC_PERCENT 100



:start
start "ETHMiner" %executable% %commandline%


[/code]