A few things were causing the crashes:
1) preventing the card from going to P2 state
2) Applying overclocks while the pill was running
3) Trying to run the cards with PL under 70%
I am now able to set my clocks and power limits with nvidiainspector, run the pill and have Claymore happily hashing.
I'm getting approx 36 MH/s per 1080 at +0/+850/70%PL but hashrates sometimes fluctuate, indicating that I'm probably dealing with mem errors so I must be close to max mem clocks.
@heavyarms1912: is ETHminer clearly better than Claymore? Is it the reason you're getting over 41 MH/s on a similar setup?
Were you using the EVGA overclock tool or another one? With the official overclock tool I had no issues out of the box with ETHlargment and Claymore. But I'm using a 1080ti, you said 1080 so I don't know if something is fundamentally different between the two cards.