Power-On Anomaly - Need Advice

Destruya

Limp Gawd
Joined
Jul 15, 2007
Messages
405
Okay, so for about the last three months or so, my computer's been doing something odd. When I shut it down, sometimes it won't power back on until an indeterminate amount of time has passed. Sometimes I can get it to cycle by unplugging the PSU's cord or toggling the switch in the back and counting to 30 or so.

The motherboard's 'power' LED stays lit even when I remove the cord, which I find *odd*.

The PSU in question is a Seasonic Platinum 1000W (not even half way through its 7 year warranty), and the motherboard is a P8Z68-V Pro/Gen 3. The computer is connected to a BR1500G battery backup with the booster pack (over 150 minutes of extra uptime under low load, and over an hour under heavy load), and because this particular UPS has crappy surge protection figures, the BR1500G itself is plugged into an Tripp-Lite ISOBAR surge protector (and only the computer and monitor is connected to it, as I don't like the idea of surge-on-surge).

It's only upon shutdown and attempted restart that this issue manifests - whenever I set the computer to restart, everything works fine. I've also gotten the computer to partially turn on during these 'episodes' by moving the plug to the second battery backup, but it's only for a second or so.

Just from my limited electronics knowledge, I'd say a capacitor (or capacitors) somewhere is/are going awry, but I figured I'd post here and see if someone else could nail down whether it's likely to be a motherboard or PSU problem.
 
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The LED staying lit is normal, power supplies have capacitors to store energy.
They take time to discharge when power is removed.

Check your 3V CMOS battery isnt low on power.

Try using the PC plugged directly into the wall, see if the problem goes away.
 
The LED staying lit is normal, power supplies have capacitors to store energy.
They take time to discharge when power is removed.

Check your 3V CMOS battery isnt low on power.

Try using the PC plugged directly into the wall, see if the problem goes away.

The CMOS battery is something I hadn't considered (and honestly should have), and I have tried plugging the computer directly into a non-backup surge protector. The system's ~3 years old now, so it's entirely possible that might be the culprit.
 
I just went through something very similar with my system...

http://hardforum.com/showthread.php?t=1830159

...new PSU, problem solved. I am guessing it has something to do with the protection circuit on the PSU, that requires a certain amount of time to pass before it will power back up.

Well, people are saying that early models of my Seasonic Platinum 1kW had 'bad caps' on the Hot Deals forum. I guess that seven year warranty will come in handy - now to just get my hands on a PSU that'll run my current system in the interim, unless I can convince Seasonic to do a 'send me a new one and I'll send the broke one back in the new one's box' deal.
 
Yeah - I plugged in a new PSU after shutting the old one down and it fired up on the first press. Still might change the CMOS battery, but not until I go through and take down all the settings in the BIOS I changed way back when.
 
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