@tytanik - i experience the same issue issue like most of users with NV and more cards.
H110+ 13 x P106 setup, found everything from the start, have the following problems:
1. Overclocking works pretty strange, to clock the memory of the P106 from 4000 to 4900 i needed to put 1600 as parameter. Steps that increase the MHz are really not relevant. Putting 900 clock to 4400 something.
2. Finally stabilized the machine to 325MH and runs well but it reboots without reason 14 times for 10 hours. Temperatures are under 65C, target is 76C.

So how to fix those nonsense reboots ?