PC won't turn on after i unplugged it...

[Eidoss]

So this evening i was playing my games having fun but suddenly it started to rain and thunder and everything so i turned off my PC, unplugged it went downstairs... hour later i plug it in hit the power button and all i see is my lights on my keyboard and mouse turn on for a second then they turn off and so on and they'd keep doing that.. i unplug all USB ports... I turn off the PSU... I try everything so i gave up and went to sleep, decided that i'll just take it to the local PC shop... but then! In my last hope I unplug everything turn off the PSU wait for a few seconds plug it all in and it works!!!

But what if the same happens again?! But my solution doesn't work? And why did this happen in the first place?
Also this PC is working perfectly built it last month, all good...
My PSU : OCZ Fatal1ty 550W

 

[Dextre]

I have what appears to be the exact same problem. I also unplug my machine if away for long times or during thunder. If I restore power all I can see is that the motherboard lights up the power and reset button. I have those available on the board itself as well. The PC however does not start. Nothing not even fans spinning up, no post, no sign of life other than motherboard lights. Starting up via motherboard button doesn't work either. I didn't have any solution so I just tried everything, plug, unplug, turn off PSU main switch and back on, everything. After about 50 pushes on the power button it suddenly starts and everything is just fine. If I keep it plugged the problem doesn't show. This has happened after all recent unplugs. What could this be?

PSU: Hiper HPU-4S435 (rated 435 W peak 480 W, works absolutely fine when the PC runs)
Motherboard: ASUS P5Q-E
Others: Win7, 4 Gb RAM, Core 2 Duo 2,8 GHz, ASUS GTX 660

 

[JeckeL]

But what if the same happens again?! But my solution doesn't work? And why did this happen in the first place?

Sometimes capacitors and so-forth need time to either build up charge or need power to be discharged/flushed from them. Keep in mind; even if you have the power cable unplugged there may still be residual power moving around/fluctuating throughout your system.

I would get a surge protector so that you shouldn't need to worry about unplugging your system in a storm.

I have what appears to be the exact same problem.

I would try disconnecting power cable and all power connections within the machine, then press the power button multiple times and then hold it in for like 30 seconds (nothing will happen, all cables are disconnected), then reconnect all system power cables and the power cable to the wall outlet, let it sit for a few minutes and try powering it on.

 

[westom]

But what if the same happens again?! But my solution doesn't work? And why did this happen in the first place?

Symptoms can apply to maybe thirty different reasons. Some will suggest one as the only viable reason. Others will invent popular myths such as capacitors needing long time to discharge. Total nonsense.

An example. Your system has two power supplies. Once one starts, it remains always operating. But when first starting, a bootstrap resistor is necessary to get it started. That resstor only has one function - to start the 'always on' supply. But if the resistor has changed or even failed, then the 'always on' supply may start intermittently.

Does that explain your fault? Well, as a computer assembler, you should have learned how to determine if that 'always on' supply has started from functions or indicators unique to your build.

Same applies to all other 'suspects'. With information provided, every reply can only be wild speculation. Your replies will only be as useful as information you first provide. Best information comes from a digital meter. To 'see' what exists when the system does not start. Using a tool that any junior high school science student should have learned to use. Only then do facts exist to reduce the number of suspects to single digit possiblities.

BTW, this defect could have existed even when the system was first built. For example a manufacturing defect that is slowly getting worse with age. Just another reason why you know the list of possible suspects is quite long.

It should be obvious to all that a 'charing capacitor' is classic hooey. Capacitors charge and discharge a hundred or millions of times every minute. A capacitor that takes minutes to charge could never do its job as a power filter. But some feel. Then use those feelings to know it must be. Instead, one should learn what the part does before making any recommendation. The meter is another example of 'knowing something' before making any conclusions.