Modular PSU's have different circuitry inside them a lot of times. Honestly, its just a nicety Modular cabling isn't necessary.
So far I have found there to only be 3 very reliable Modular PSUs: Seasonic M series, Antec Neo series, and the Corsair series. Seasonic being the best and Corsair very close as they both run off of Seasonic parts and design.
PCP&C is unnecessary, especially for your system. I would recommend a 500 Watt Seasonic power supply. Quiet and one of the most reliable PSU's out there. If you don't like it for some reason then Fortron, Antec, PCP&C, Zippy/Emacs, Silverstone, Corsair (etc...)).
As for the high pitched squealing noise, my best guess without hearing it is just normal capacitor whine. Why it became audible after the thunderstorm? Coincidence? I honestly wouldn't worry about it unless you begin to notice power fluctuations across the rails.
-Kevin