If you are messing with the voltage pot without having the usb power meter in on a stick already having issues you are basically shooting in the dark.  I’ve seen people try to tell you that you can do it without it, but again it doesn’t always work.

And Sidehack is right they test for 24hr and every one of mine has been fine at 400mhz from the day I got them.  Some did get finicky as I went higher, hince why I literally have hours tuning every single stick individually to run them where they are today at 575mhz.

Also what are you using for cooling?  The fan you maybe using may not be enough especially if you have tweaked the voltage and it’s now too high.  I’ve had some that even slight adjustments went to stupid amounts fast and they would get INCREDIBLY hot.

Also what is your start script like what voltage do you have them ramp up from?