My current PC build is about 5 years old, I have a 650 watt BFG PSU. From about the first month I had it installed I would get a random occurrence of pushing the power button and the lights would come on and then shut down almost instantly. When this would happen I'd have to unplug the AC cord and turn the main switch off and then put it back together and it would be fine. In my thinking it was the switch on the case or something. A couple days ago it happened and it just wouldn't come on. I unhooked everything, opened the case and checked for excessive dust and any loose connections or whatever might be wrong I really wasn't sure, couldn't find anything so I put it together and it fired right up. The night before I had swapped a Nvidia GTX 550 Ti for the ATI card to see if it looked any better.. IL-2 BoS ran better with no micro stutters but pretty much everything else looked like crap so I switched back to the Radeon and went through all the headaches associated with removing all the Nvidia stuff and putting all the correct drivers back in. So I'm playing GTA V and had been in an extended chase of another player with whom I'd been trading shots with and just as I'm about to take him out there was a rather loud bang and everything went off, the dog who had been sleeping under my desk and is never quick to move shot out from under my desk like a rocket and I thought at first he had gotten tangled in the power strip but all the plugs were in place. Just as I stood up there was another loud bang and a shower of sparks erupts out the back of my tower *Holy Sh.. I snatch the AC cord out of the back and look to see a puff of smoke and the distinct smell of burnt electronics..

So of course I'm disheartened by this turn of events, then I get a call from my Dad who is always collecting computer parts (read discarded by the roadside) and he tells me one of his R/C club buddies gave him a PC that he threw out because it was overheating, it turns out that it was packed full of dust and dog hair and after he cleaned it out it has a MSI P67A G43 Motherboard a XFX Radeon HD6870 vid card and a Thermaltake 850 watt PSU and no HDD. Dad said that I could cannibalize it or just put my stuff in it if my MB is fried. Now I don't know much about Intel products and I really wanted my AMD board to work so I just stacked them and ran the needed connections and lo and behold the board posts, Thank the PC Gods.
The PC seems to be happy and the extra bump in the specs of the Vid card runs everything a bit smoother, lucky me

I had that happen to a CTR monitor back in the mid 1990s. A power supply filter cap (large one) exploded. They can be as loud as a gun when they go!

Glad you are back to gaming!

I actually opened up the PSU, the two big Caps (about the size of my thumb) are both bulging on the top so that was the two loud bangs.. I lucked out for sure

Just FYI, if it's just the caps, and the PSU is worth it, replacing the caps is very cheap.

And remember when you open PSU next, there's enough residue voltage in them it could kill you

Yes, Col. this I'm aware of however many don't know that a capacitor is like a battery but while it might not have high voltage it's the amps that are dangerous.

When I was stationed at RAF Lakenheath around 2000-2002, I was under my desk in my dorm room, working on my PC. In those rooms we had outlets for both 220 and 110, but of course the plugs are different to keep you from mixing them up. Well apparently when I unplugged it before working on it, I had accidentally flipped the switch on the back of the PC to 220..... can you see what's coming here?

I still had the case open when I went to plug the PC in, and was lying on the floor next to the PC. When I hit the power switch...

It was LOUD and went off right next to my ear. My ear was ringing for a few hours and the room stank of electrical smoke. I later made a trip to the electronics store in the BX and bought a replacement PSU... and lucked out, because everything else in the PC worked fine! I was only out about $75.

We used to 'accidentally' flip the switch on the pcs at an old workplace as it was the only way we could get the old pieces of junk upgraded.