Dead power supply?

[quaxo]

Well, woke up this morning to find my computer (which was on the night before) off. Had some wind and rain last night and figured the power must have gone out in the night. (My computer specs are to the left in my profile. Build is about 2 years old, all parts new at that time.)

Now, the computer won't turn on. Pressed the power button, no lights or fans or anything, like it's not even plugged in. I checked the power outlet and it's fine, checked all the power cables and they all seem in order.

Normally, some USB devices (like my unpowered USB hub and mouse) stay lit even with the computer off, but they're all off now. Even the little green light on the motherboard isn't on.

I figure something has happened to the power supply, but before I go and shell out for $75-$100 for a new power supply (the system needs at least 600w and a power supply that supports 2 graphics cards, and I don't buy cheap stuff), just wanted to get a second opinion. Would there possibly be anything else such as the motherboard? Even with the motherboard damaged, I figure something would still have some kind of power, like the USB devices as I described, but nothing, which leads me to believe it's more likely the power supply is shot.

What do you guys think?

[patio]

Unfortunately the PSU takes the 1st hit in these circumstances...is there any way of borrowing 1 of the one or greater wattage to test ? ?
Meantime unplug the existing unit and toggle the rear on/off switch 5=6 times and re-plug it.

[quaxo]

Unfortunately, I don't know anyone with a system like mine or one I could borrow. I suppose I could use a lower wattage one just to hook it up and see if the stuff lights up like it should, even if I don't turn it on. At least that would give me some kind of answer as to if it's the power supply. I might have one here at the shop somewhere that will do.

The only other thing that I could think of is that the motherboard took a hit that has stopped it from letting power through to the USB stuff when it's off or recognizing that the power button is being pressed, but I thought that would be unlikely. I haven't noticed any damage to the motherboard on a visual inspection either, but I know that doesn't mean that there couldn't be something wrong with it.

I had already tried everything I could to get the PSU working again, including what you suggested. Still no response from it. I think I'll go ahead and try a lower wattage one, just to see if things light up as I said. We'll see how it goes.

[DaveLembke]

Just wanted to mention that a UPS is a good investment. I have 4 of them. Flatscreen TV & cable modem is hooked up to 1, and have 3 others on 3 other computers. If a UPS is too expensive, a surge supressor is a must to protect power supplies from getting spiked.

Personally I like UPS's better as for your computer will stay running for 5 or 10 minutes depending on draw and UPS VA rating. For quick power outages they keep your computer running as if nothing ever happened, as well as if yo have an extended outage and plug in the USB remote cable that comes with most APC brand UPS's with the power management software installed, you can have the UPS safely shut down your computer when the UPS is drained to 20% battery life to avoid data corruption. This is handy if computer is running and your not home or awake to shut it down safely.

Only annoyance of UPS's though is that they beep repeatedly during an outage to inform you that they are running, so they can be annoying if trying to sleep and you get an outage at 3am. Some have a option on them to silence, most dont.

[quaxo]

Well I'll be....

I tried everything I could think of to get that thing working this morning. Unplugged it for an hour, disconnected it from EVERYTHING, played with the switch... nothing worked. Left it unplugged before going to work.

Came home now, and for grins plugged it in and the USB hub light came on. Pressed the power button and it started right up. Guess it just needed to sit there a while longer. Seems to be working fine for now.   

That is of course after I stopped by a friend's shop on the way home and borrowed a Raidmax RX-730SS. Oh well, guess I can take it back to him tomorrow and tell him I don't need it. 

Thanks for the help anyway guys.

[patio]

Come to think of it I've had that happen as well...not sure what type of nreakers they use internally for protection...but some take longer than others to re-set with no power to the unit...

Glad to hear you are fixed up and not having to replace a Mboard/CPU combo....

[Computer_Commando]

A crowbar circuit once triggered, pulls the voltage below the trigger level, usually close to ground. A clamp prevents the voltage from exceeding a preset level. Thus, a crowbar will not automatically return to normal operation when the overvoltage condition is removed; power must be removed entirely to stop its conduction.

[truenorth]

CC,For further edification re  your explanation re "crowbar" given that power supplies normally do retain voltages for significant times even after being deprived of a power source would this explain why in quaxo's case it took a passage of time before the effect of power on the crowbar would have endured? We also don;t know if quaxo ever removed power from the computer.truenorth

[Computer_Commando]

Yes, I think that would explain it.
Crowbar could be a feature of his PSU which might only be found on more expensive ones.  None of mine have this feature or it's never been displayed to me before.
More info:  http://en.wikipedia.org/wiki/Switched-mode_power_supply

[truenorth]

CC,Thank you,truenorth

[quaxo]

We also don;t know if quaxo ever removed power from the computer.

Then you didn't read enough  I did say.

It remained unplugged for an hour and still didn't work. Then I left it unplugged while I was at work, so about 10 more hours it was left unplugged before it started working. So, the magic number was somewhere between 1 and 10 hours. 

[truenorth]

quaxo, and so you did--my error.seems like CC has shone a light on what has taken place.Most interesting.truenorth