I'm confused... Your topic title talks about a 'brown out' event, then your first sentence talks about a 'surge' So which is it?
OK, might have well been both. Let's say that a creature (a fox bat) got across your mains. For the duration of the time it takes your mains to fry the poor sucker, you'd have 'brown' power. ie, All of the mains AC would sag , thus your wall socket would get (say) 10% or so less voltage. Your surge protector has no fill-in capability, so now your PSU is under-powered, but still requires the same watts output so P+I*E takes over... 'E' went down, so to maintain 'P' 'I' HAS to go up. Thus overloading your psu. If it is a good PSU it might take the load....
Then the poor creature that caused the event is fried free of the mains. Suddenly, your wall socket is now hit with a surge of voltage and again most likely your surge suppressor can't handle that kind of transition. And now your PSU has to react.
In order to keep this from becoming a tome on AC mains, surge protectors (unless very good / expensive ones) won't protect you from surges. And the very expensive ones won't cover you from brown outs for longer than their caps can store a supply, typically milliseconds.
I'd guess that your PSU is fried, and also possibly your GPU. You might also expect your memory to show degraded performance in the near future, as well as possibly your MB...
A decent UPS can be worth a lot.