Your mem clock is extremely low for this type of memory. Set it to 5400 at least, also delete the intesity setting. HSR miner will do the job for you and set it better. Also if you have such low temp, maybe it is not good idea to lower power limit especially for neoscrypt.
Letting hsrminer set intensity has resulted in a mysterious drop in hashrate by 100-150 kH/s after 1-3 hours of operation, and this is with two separate GTX 1080 on two very different machines. But in the spirit of science I'll try your suggestions. I noticed you don't mention anything about core clock, though, and that seems to be the source of woes for me.
Right now my Asus GTX 1080 ROG Strix edition is hashing at 1208 kH/s while drawing 166W at 85% PL, -125 core (varying between 1595 to 1670) and +300 mem (4811). (while typing this the hashrate dropped to 1176 kH/s... sigh).
My older EVGA GTX 1080 FE is hashing at 1218 kH/s while drawing 146W at 85% PL, +125 core (1633 to 1658) and +300 mem (4811 again).
In both cases setting -i 4 resulted in about 100 kH/s lower hashrate but with no real change in stability, at least for the FE card; I didn't bother repeating the same experiment with the Asus.
I've found that too much of a memclock boost creates instability (and I haven't seen any benefit), though maybe it's because I have different cards. I'm running about +150 core and +200 mem at 80% power on 1070 and 1060 3G, getting a slight hashrate boost but extremely stable. Around the 1700/4000 range for both, and 1160kH/s and 740kH/s on 1070 and 1060. Also getting 500kH/s on 1050 Ti @ stock clocks and 80% power, all very stable.
