Hashcat 1080(s) gpu error

I have a 5x 1080 build.

2x psu

Sometimes (please note sometimes as if i restart the rig there is times where they will all run fine) when running hashcat I get this error :

nvmlInit(): GPU is lost

NvAPI_GPU_GetBusId(): NVAPI_ERROR

NvAPI_GPU_GetBusId(): NVAPI_ERROR

NvAPI_GPU_GetBusId(): NVAPI_ERROR

NvAPI_GPU_GetBusId(): NVAPI_ERROR

NvAPI_GPU_GetBusId(): NVAPI_ERROR

NvAPI_GPU_GetBusId(): NVAPI_ERROR

and either 1 or 2 of my gpus will be no longer run.

Help?