My PSU goes BOOM!!!

Today, recently my desktop PC goes boom after shutdown itself, don't know why since the CPU case is open that left more room to breathe.

According to this forum here, it says that due to brown-outs (most likely frequent one) will make PSU (Power Supply Unit) to break just like mine.

After that boom, I remove all the components and check each if not only PSU fault. And almost forgot that I have extra 500W PSU - Thanks God. Removed the PSU, quickly changed to extra one and there you have it. It run again.