mind sharing your miner, settings and driver version?
Here's mine:
CPU: Intel Xeon E5-2660v2
GPU Driver version: 390.144
CUDA version: 9.0, CUDA runtime: 8.0
sudo nvidia-smi -pl 158
DISPLAY=:0 nvidia-settings -a [gpu:0]/GPUGraphicsClockOffset[2]=+145
DISPLAY=:0 nvidia-settings -a [gpu:0]/GPUMemoryTransferRateOffset[2]=1850
=> 48C P2 161W / 158W
ethminer 0.18 or PhoenixMiner 5.4c
both need ethlargement (-straps 2 does nothing)
=> 36.7Mh/s