OT: Unplug that computer!

blink3times wrote on 7/30/2009, 5:16 AM
Had a neighborhood power failure sometime during the night. The computer was OFF, but none the less I had a hell of a time booting this morning. I thought I was somewhat protected with the machine off in times of power failures.... but not so.

Had to go into BIOS this morning and adjust all the memory/cpu voltages.... very strange.

Comments

John_Cline wrote on 7/30/2009, 5:33 AM
Unless it was unplugged or on a switch, it wasn't actually off. The power supply provides +5VSB “standby power”. This output is always turned on even when the computer is turned off, which allows the computer to turn itself off without requiring you to press an on/off switch. It also keeps the power to the keyboard, mouse ports, usb & memory on all the time as well.
Former user wrote on 7/30/2009, 5:45 AM
Check battery on Motherboard.

Dave T2
farss wrote on 7/30/2009, 5:56 AM
That's why there's an On/Off switch on the back of the computer.
If you have problems with mains surges and/or lightning the only way to be sure it's safe is to unplug it.
Even then...I've got one tangled mess here whereby I can turn one PC Off and it continues to be powered from another one thanks to a USB interconnection. Near need to drive a stake through the thing to make the fans stop spinning.

Bob.

craftech wrote on 7/30/2009, 6:05 AM
Press Ctrl - Alt - Del and it may have booted properly the second time.

But some motherboards exhibit this problem with some BIOS versions or all BIOS versions, yet others do not.

Some BIOS have a setting called "power on" vs "last state" that deals with a power loss.

"Stay off" tells it to stay off - not to boot back up when power comes back on.

"Last state" tells it to boot up if system was on, or stay off if system was off

"Power on" tells it to power on when power comes back on.

Check that setting if you have it in your BIOS.

John
ECB wrote on 7/30/2009, 6:46 AM
Did you check the line voltage? The outage many have been accompanied by over and under line voltage. If that occurred duing auto POR then maybe your BIOS settings were changed.

Ed
musicvid10 wrote on 7/30/2009, 10:36 AM
Any power / lightning hit may damage the power supply whether the computer is on or not.

Run a voltage diagnostic from your motherboard manufacturer and try a different power supply if anything is low or varying more than 5% (the +5V normally runs 2% low on VIA chipsets).

A replacement PS is cheaper than replacing a motherboard and then finding out it really needed a PS. That comes from experience.
A. Grandt wrote on 7/30/2009, 10:55 AM
While in the bios, check the clock. I don't know how common it is, but my old HP Laptop once did reset it's bios clock to 21 December 9999 after a power failure resulting from a 1.5m drop that must have done something to scramble it's bios memory.

Windows XP is NOT even remotely Y10K compatible, and never recovered after having been booted on that date, even after it was corrected.
rmack350 wrote on 7/31/2009, 1:52 AM
Oy, that USB connection makes it even more complicated.

normally, your best protection is to unplug the machine.

A power surge or lightning strike could travel up a neutral lead. Very few switches will break the hot and neutral so a switch is usually not much protection.

Rob Mack
ushere wrote on 7/31/2009, 2:11 AM
all my pc's go through ups - all of which carry HUGE guarantees against anything nasty happening.

hope i never have to find out.....
blink3times wrote on 7/31/2009, 4:39 AM
Line voltage is the only thing I can think of... everything else however was functioning fine (plasma tv, stereo, cable boxs.... etc) but then power supplies are SUPPOSED be able to deal with slight variances.

-BIOS battery fine
-Power supply brand new (all voltages check fine)
-system is surge protected (surge indicator was not tripped)
- system set to "stay off" in power failure (cntrl/alt/dlt had no effect)

The only thing that got me back on line was to raise the cpu and memory voltages a couple of notches in the bios...... very strange!
JJKizak wrote on 7/31/2009, 4:59 AM
If the lightning hit is close enough it doesn't matter if the computer is plugged in or not. It will be toast along with the house. (Close means real close) However with it plugged in a nearby lightning hit will travel and surge through any wire available. And sometimes the ball lightning will just bounce around through anything it wants to. My neighbor just had lightning rods installed on three of his 110 ft tall trees.
JJK
musicvid10 wrote on 7/31/2009, 5:58 AM
"The only thing that got me back on line was to raise the cpu and memory voltages a couple of notches in the bios...... very strange!"

That suggests a partially fried neutral somewhere on the motherboard, main power connectors, or in the PS itself, probably in the return for the +5V. High resistance is the result of overheating; the monitored voltages might look fine at idle, but drop under a data (current) load. IOW, you're getting the volts, but not the necessary watts.
blink3times wrote on 7/31/2009, 6:51 AM
Everything tested... all fine. CPU and GPU tested both at full load at the same time for an hour (Q6600 and GTX 275). All temps monitored.... runs at full load without issue. Everything works just as it did before. It's just that one booting issue after the power outage that was the problem.
[r]Evolution wrote on 7/31/2009, 8:33 AM
I feel that any Professional Workstation should be connected to a Power Conditioner/Battery Backup.
I have experienced 'Dirty' Electricity, Surges, and Power Outages both before and after my Conditioner/Backup.
Before = Problems
After = No Problems

My Conditioner/Backup has software that detects when it's running on Battery power and Shuts Down the computer before it just Crashes sans power.

This $100 investment could save you Thousands in the long run.
John_Cline wrote on 7/31/2009, 8:42 AM
I just assumed that everyone was using a battery backup. If you're not, then you certainly should be.
Jay Gladwell wrote on 7/31/2009, 10:03 AM

"I just assumed that everyone was using a battery backup."

Yes, sir! Here in Miami it's a must. FP&L provides such crappy service (power goes out on clear sunny days!) that to do otherwise is... well, you know.

The APC unit I use has a program that saves all open all files and shuts down the computer if the power is not restored within 5 minutes. It's saved my bacon on a number of occasions!


GlennChan wrote on 7/31/2009, 1:05 PM
A replacement PS is cheaper than replacing a motherboard and then finding out it really needed a PS. That comes from experience.
I agree.

A friend's power supply died spectacularly, and it took out the motherboard, possibly the CPU (don't know), and both of his hard drives.

I would not ignore a bad power supply (or damaged capacitors)... not worth the grief because bad power will damage components.
musicvid10 wrote on 7/31/2009, 4:08 PM
[i]I would not ignore a bad power supply (or damaged capacitors).

Equally true, Glenn. It doesn't take much ripple to cripple . . .
GlennChan wrote on 7/31/2009, 4:19 PM
This is what the power supply did:
http://www.glennchan.info/Proofs/forums/ars/hdd-fry01.jpg

The chip burned up, burned through the foam, and left a souvenir behind on the hard drive.
lynn1102 wrote on 8/1/2009, 3:21 PM
That looks nasty. Years ago, during my early linear editing day, I had a long project almost completed 3 times, and got zapped 3 times in one week. Each time I had to start from scratch. Been using a ups ever since on each system. We do get a few brownouts during the real hot part of the summer, but we also get lots of monentary outages - just long enough to have to reset about a dozen timers and clocks. Computers keep on ticking like nothing happened. Even close lightning strikes don't bother it at all.

Lynn
John_Cline wrote on 8/1/2009, 3:41 PM
I'm lucky enough to get my electricity from PNM, which has the best up-time rating in the country. My UPS keeps a log of the power interruptions and the last one was 22 months ago and lasted for 2.5 seconds.
richard-courtney wrote on 8/1/2009, 3:42 PM
John,

I use that fact for something called "Wake on Lan".

I can use a special command from home to wake up the office computer
so I can grab a file without driving back to the office.
blink3times wrote on 8/1/2009, 3:51 PM
"I'm lucky enough to get my electricity from PNM, which has the best up-time rating in the country."

Power outages are never really a problem here either. We're a power generating province with many hydro dams. In fact we sell power to the USA. But then none of that stops something like a car careening out of control through a larger hydro pole with multiple transformers on it. (which apparently is what happened on this particular night)
farss wrote on 8/1/2009, 4:03 PM
Worst "power surge" we ever had was in a new power station. Somehow someone connected 11KV to our 415V supply. Lots of smoke got out.
Probably the most damaging oops we made was before I joined the company. A syncroscope was connected the wrong way leading an operator to connect a 500MW unit to the grid out of phase. The generator suffered some spectacular damage and the event was recorded on chart recorders 1,000KM away in another state.
One of the most common causes of power blips is faulty tap changing gear in substations. This a UPS will save you from. A hit from lighting is another matter entirely, all that energy is going to go somewhere. You can try to mitigate the damage with surge diverters but you need to think through carefully where they're diverting the energy to.

Bob.