Overclock issues

Hello a few months ago I over clocked my CPU. I pushed it to far and as such my pc wouldn't go to POST. I cleared the CMOS and it still didn't start. I removed the battery for awhile and that seemed to do the trick. Unfortunately my system was unstable when I play games. I'm having frame rate issues and sometimes the screen just freezes. I did a clean install of windows on a new hdd, used a different gpu on an different motherboard and still had the same issues. I stress tested the CPU and ram and had no errors. I tested psu with a multimeter and the voltages were fine and I switched to another psu. I'm running out of ideas on why I'm having these issues. I have my bios set to default. Does anyone know anything I'm missing?