Send detail specs of your system build including OS and version MOBO BIOS version CPU chipset driver version what PSU you are running and if each power port on the GPU has its own dedicated power cable from the PSU to the GPU amount of system RAM and what configuration it is set in and storage devices type and capacity. Case type cooling devices and number of fans will be helpful to determine if your getting proper airflow.
Do not use PCIE pigtails this will cause unstable power flow to your GPU.
Also send Idle and load temps of your CPU and GPU.
We are going to need much more detailed information to help solve this issue.