Erratic power consumption and occasional stopping

I am using grin-miner 1.0.2, on ubuntu 18.04.1, mining with 4x nvidia gtx 1070 ti’s.

At the wall power consumption is fluctuating every second or so between 650w and 730w (that’s a little much right?) grin-miner shows a steady mining rate, however nvidia-smi also matches the wall power consumption displaying rapidly fluctuating power consumption, a screenshot of nvida-smi is shown below (in the capture instance, you can see the top 2 gpu’s running at only ~60w, a second later they will show back to 140w and back again, all 4 gpu’s are showing this behavior) any ideas what is going on?

EDIT: I forgot to mention that on top of this, occasionally (perhaps once an hour) the miners will drop down to 10w usage for about a minute, fans turn off, wall power goes to ~100w all the while grin-miner displays normal operation. Another mystery.

I suspect part of the same problem, but here you can see occasionally grin-miner will display nonsense GPS (each gpu seems to be mining 2.7 gps, while the sum (2.7 x4) is obviously not ~20 gps)

There is power spike initially in the solver followed by a calmer period. The whole trimming process takes around 300ms so the nvidia-smi is not able to smooth that out. It is not doing same work every millisecond.