what settings you have there? but 6900kH/s is low
I see if my CPU i7 7700 is use like 20-30% (for example let the Suqa Wallet to do some cpu mining) I get 8000kH/s
If your electricity rate is low you can go with bad kh/w
In my case, if I was using your setting I would make 1.76$ with 10 cards (i have 24) but with my setting i make 2.47$ once electricty is paid with a rate of 0.1525$/kwh
At a rate of 10c/kwh with my settings I would still make more.
The break even point is between 0.07 and 0.08c/kwh
My settings are 0.6375v +400 core -600 memory with nvinspector
How come these cards dont crash ? I mean basically ive never seen a card go beyond 250 cc with low voltage point. What is your power draw (in nvidiainspector) per card ? Also what is current clock shown ?
With 0.6375 you can set +400 core but this doesn't mean they are actualy at this clock. Actualy nvinspector give a current clock of 1190 which is actually 400 under the default but gpu clock shows 2000mhz.
I must admit that this part escapes me because if I set the clock to +0 my hashrate definitely crumbles.
nvinspector gives 63w per card
Just test with this settings in a bat file from nvinspector folder and thank me later

SET VOLT=637500
SET MEMORY=-600
SET CORE=400
SET GPU0=-lockVoltagePoint:0,%VOLT% -setBaseClockOffset:0,0,%CORE% -setMemoryClockOffset:0,0,%MEMORY%
SET GPU1=-lockVoltagePoint:1,%VOLT% -setBaseClockOffset:1,0,%CORE% -setMemoryClockOffset:1,0,%MEMORY%
SET GPU2=-lockVoltagePoint:2,%VOLT% -setBaseClockOffset:2,0,%CORE% -setMemoryClockOffset:2,0,%MEMORY%
SET GPU3=-lockVoltagePoint:3,%VOLT% -setBaseClockOffset:3,0,%CORE% -setMemoryClockOffset:3,0,%MEMORY%
SET GPU4=-lockVoltagePoint:4,%VOLT% -setBaseClockOffset:4,0,%CORE% -setMemoryClockOffset:4,0,%MEMORY%
SET GPU5=-lockVoltagePoint:5,%VOLT% -setBaseClockOffset:5,0,%CORE% -setMemoryClockOffset:5,0,%MEMORY%
nvidiaInspector.exe %GPU0% %GPU1% %GPU2% %GPU3% %GPU4% %GPU5%