When I rebuilt a couple of years ago the supplier made a strong recommendation that for any AMD CPU (after a Pentium MMX)I should go for a 300w. PSU.
Nowadays the suggestion is 400w! I think that is a bit over the top for many, and there is an extra fan (potential noise) on the downside.
You really should go for at least 300 watts because if this isn't the present cause of trouble it could be very soon.
The design pays great attention to exact voltages, so that when the demand for milliamps exceeds the capability of the PSU, the voltage may drop out.