if you have an nvidia gpu like a gtx 1070 or a 1080, here is the best way to set it up for mining ethereum. 

apt-get install linux-headers-$(uname -r|sed 's/[^-]*-[^-]*-//')
apt-get install -y linux-headers-$(uname -r)
apt-get install nvidia-driver nvidia-cuda-toolkit

nvidia change fan settings (in this example we are setting it to 70%)

nvidia-settings -a [gpu:0]/GPUFanControlState=1 -a [fan:0]/GPUTargetFanSpeed=70

and for setting the gpu overlock we use GPUGraphicsClockOffset
and for setting the memory overclock we use GPUMemoryTransferRateOffset

nvidia-settings --assign "[gpu:0]/GPUGraphicsClockOffset[3]=100" --assign "[gpu:0]/GPUMemoryTransferRateOffset[3]=1200"

you can change the gpu:0 to gpu:1 for each extra gpu you have.

if you get an error when trying to do this you need to add the folowing variable before the nvidia-settings ...

DISPLAY=:0 XAUTHORITY=/run/user/111/gdm/Xauthority 

you use ps a |grep X 

and you will get a line like this

tty7     Sl+    0:00 /usr/bin/X vt7 -displayfd 3 -auth /run/user/111/gdm/Xauthority -background none -noreset -keeptty -verbose 3

and you put the variable infront of -auth for your  XAUTHORITY=

you can also do nvidia-xconfig --cool-bits=28 if the overclock doesn't work

now for limiting the power consumption (under clock)

 nvidia-smi -pm 1 #for presistant power limit or it will stay the same after a reboot

 nvidia-smi -i 0 -pl 140 #the pl is for power limit, in this example i'm limiting a 150w card to 140
-i is for choosing the first gpu

you can run nvidia-smi to see your gpu usage.

my recomendation is to run your gpu under 72 degrees