what mining option you have with your gtx 1070ti that you see you get betther results ?

and anyone can help me, i have one rig with 13 gtx 1070ti with afterburner to operate the OC, when the rig start all the fisrt all goes well but after some hours it has some drops hash in some gpus what could be, also notice the pc get a lot more slow, i have 2 psu with 2000w each and also changed the gpu's so the problem is not the gpu, not the psu(i think) and not the risers what could be ?