Try all of these in this order:
Make sure all the wires from the psu are tight.
Remove the undevolt.
Remove xmp if enabled.
Go to the bios and put all cpu and ram settings to default.
Run ram at 4800.
Try all of these in this order:
Make sure all the wires from the psu are tight.
Remove the undevolt.
Remove xmp if enabled.
Go to the bios and put all cpu and ram settings to default.
Run ram at 4800.