I experienced the same problem 7 months ago, every single month I bought a PSU to replace it up to 3 months 3 PSU. I've been frustrated with that the problems, all the ways I have been done for the fix including advice members like above.

finally, I have found a problem is an electrical voltage in my home not stable (after using a watt meter like Kill A Watt Meter in the USA) because of a cable used not corresponding a procedure or standard for electricity voltage used after the electrician replaced the cable, Mining Rig back to normal and the PSU or USB Riser cable never melt again.