In that case, probably not. What it could be is a "heat" issue. I'd check to see what the core temps are when you get up and running at normal load. Perhaps, the interior has collected alot of dust or the heatsink and cpu fan aren't properly cooling the system and once it reaches a certain temp, the pc will automatically shut off to not do any more damage. I'd argue that's a probable cause.
A PSU going out could show symptoms from merely not turning on all the way to a shower of sparks and smoke/fire. You might look around to see if the mobo has burn or scorch marks, same with video card... maybe bulging or burst capacitor on mobo?
It sounds like it's not the motherboard. It's possible that it's the video card that is the issue. Are you using the onboard video outlet? Does it have one? Or is it a separate video card? I had an experience with a bad AGP-bus video card. (PNY Technologies). There are about 7 to 8 capacitors on the video card. These capacitors exploded one by one. Each time it produced a loud, sharp popping noise - like a firecracker. I didn't know what it was until the video card went out. The video card still functioned after the first pop. But after the 4th pop or so (can't remember exact), the video card finally gave way. I could see clearly that the capacitors on the video card exploded inside-out like a pop-corn. Overheating, perhaps. Faulty voltage regulator, maybe. Dunno. Wonder if you are experiencing a similar issue. If so, maybe change out the video card.
God is probably telling you NOT to build computers anymore. It could have burnt your house down while you were away. I think you got lucky.....
I would say the sound of a 'pop' is most definitely associated with a capacitor(s). The good thing about caps is that you can open up the unit and inspect for black charred burn marks where the pops took place. And usually, the larger the pop, the larger the cap. They are typically, blue or brown cylinder shaped parts. Open up the case and have a look. The supply unit could be opened up at some time as well, but if it isn't dead there are other diagnostics you can use to check, such as using a voltmeter to monitor outputs are good and or BIOS to examine if output voltages are within expected range. Agree with most here that PSU is usually the culprit in your description, you can likely replace a cap at radio shack for a few bucks.
This is my old AGP-based video card. Red-circled are the exploded capacitors. 7 total. After the 6th one exploded, the card gave out.
I think that's a bit extreme. You do realize that the big box manufacturers have had untold number of pc's that went "pop" as well, blowing out PSU's and destroying all the components as well. It's got far more to do with faulty engineering on the components side than a poor assembly.
Bolimomo, It seems that this is exactly my problem. The diagnosis and picture fits. After taking a look, I have about 5 of those blown capacitors. Looks like I will be getting a new video card, though I may consider a new system still. My old one was an XFX 8600GT PCI x16. I'm not familiar since it's been 3 years, but there are PCI 2.0 and 2.1 interfaces now. Anything come to mind that can easily replace my old 8600GT?