Computer won't start, unless...

Factual Questions
1

Okay, I’m at about my wit’s end.
Shortly after a sudden power outage, my main computer started acting oddly. I hit the power button, the fans spin up for a moment, and then stop. Spin up, and then stop. Meantime, I’m not even getting to the BIOS screen - nothing but black.
I noticed, after a bit, that if I unplugged the computer, or turned off the switch on the power supply, the computer would boot up.

Things I’ve tried, to no avail:
replacing the power supply - and putting the old power supply into another computer, which starts fine
clearing the CMOS
checking memory
all plugs and card fully seated
Windows repair, and then restore (to ten days ago)
BIOS is current version, reflashed (just now)

Any thoughts?

2

A physical component is damaged, probably a capacitor. If it’s on the motherboard, well, that’s that. Inspect the mobo, looking for caps that have unusual bulging. Could try pulling one stick of memory at a time and see if symptoms stop while one particular stick is gone, but that seems less likely.

3

^^Solid advice^^

4

You can also try replacing the power cord to make sure it’s not damaged. Happened to me a couple years ago.

5

I agree that it is most likely a motherboard problem. There isn’t much you can do about those except replace the motherboard. That may not be that expensive on a desktop that you want to use a while longer if you do it yourself. It sounds like you have the technical capability to do it. You just have to buy a new one that has the right rocket for your CPU and RAM and get to work. Unfortunately, replacing a motherboard isn’t all that different from building a computer from scratch and it can take hours of careful work but it is mostly just plug and play once you figure out what connections go where. Your OS and other software may not like it either since it will think you just installed it on a new computer.

6

I’ve been building computers since about '99, so replacing the motherboard isn’t a huge deal - tedious, but simple. I’m also assuming I’ll have to reload Windows and all, though I’ll probably try it out right after the swap to see if it works.
I hadn’t thought of the power cord - I’ll give that a shot in a moment; I know I haven’t changed that.

But yeah, a bad mobo is pretty much what I was thinking; I was hoping if I didn’t mention it, it wouldn’t lead everyone else immediately down the same path.

sigh

7

I actually had the same thing happen to an older PC of mine. It was about 7 years since I built it, and following a power outage (despite being plugged into a surge protector) it began to exhibit the exact same behavior.
The problem was with the power supply. It was pretty old and tired and I guess it didn’t provide enough juice to properly boot the thing reliably.

8

Presumably you tried the power cord when you tested the PS in the other system.

9

Welp, just swapped power cords, and it didn’t work.
Timmysteve, it may not have been clear from my description, but I have another computer handy (test rig for Windows 10). I swapped the PSU’s around (though not, at the time, the cords). Problem computer still exhibiting problems, test rig starts up fine.
I don’t see any bad (looking) capacitors, but I’m pretty well convinced it’s the mobo. RAM swapping didn’t fix the problem either.

sigh

10

capacitors and other components can fail without visual indications. does make life tougher.

11

If your surge protector does not have a battery in it, it will do nothing to save you with a power loss.

On some electronics, sudden loss of power is more of a problem than small over voltage events.

Some battery backups also have a surge protection circuit. I use stand alone of good quality as we have tornado, ice, "T"storms, drunks hitting poles, wind taking out lines and … Sudden power loss is common.

Wall - cheap surge protector ( Hopping it goes first in a surge) - a good surge protector like a Triplite, etc. - Then a battery back up that carry my whole system, modem/router/wife’s computer, land line power warts - and the micro cell we need for the smart phones. ( Why yes, we have more then one battery backup. Cheap in yard sales and usually still good or just need new batteries.

Backup for the flatscreen TV is a must as sudden power loss or surge from a lightning strike is one of their worst enemies. Stuff is getting cheaper all the time and if the dice roll is OK with you, just buy new equipment and rock on.

I be poor but like good equipment. I tend to keep the oil changed, the tires inflated and clean the weapon on a regular basis. So far, so good.

12

Only urban myths cite low voltage or sudden power loss as harmful. Yes, it is harmful to unsaved data. And does not harm hardware or saved data. A sudden power off also happens when any appliance or computer powers off. How often does power off damage electronics?

If sudden power off is destructive, then he also said what parts are at risk; can be damaged. Nobody does because no parts are harmed. In fact, interntational design standards for electronics, long before the IBM PC existed, said all low voltages down to zero are not and must not be harmful. Exact phrase in all capital letters is “No Damage Region”. Because power off is only destructive when fears and wild specuation replace reality, logic, numbers on manufacturer datasheets, and well proven science.

OP’s symptons are classic of what a power controller does. Since most do not even know it exists and what it does, then many use speculation and advertising myths to recommend solutions. Recommend solutions to a problem that is not even defined.

Sound like the OP swapped out numerous perfectly good and sometimes irrelevant parts. Leaving only one item left to replace. Demonstrates why shotgunning takes much longer. And did not even identify any reason for that failure. Did not even say why a power controller kept doing a power off. We know all power offs are just as sudden to hardware. And neither low voltage nor power offs harm electronic hardware.

johnpost is perfect on target. Most all electronic failures have no visual indication.

13

LOL, well, you can just yank the plugs out of the wall on your $1000 flat screen TV but I ain’t gonna do it.

Not going to do it to my best computer either. You can if you want.

There is some difference on many electronics between using a power switch and yanking the plug out of the wall IMO. Why do they have a shut down sequence on programs and electrical systems in air liners. Much easier & way cheaper to just yank the lead off the battery or pull the plug.

Do you do that on your TV?

Also have been told that low voltage is very hard on Plasma TV’s.
I do not know anything about LED TV.s

YMMV

14

Had the same thing happen to my last PC - turns out (after a long series of trying to figure out what the hell was going on) that there was no on-board buzzer. One trip to the Place Where Old Computers Rest In Peace (i.e. under the bed) to find an old one, and I discovered that what thought was the MB starting up, waiting a bit, then rebooting was in fact it starting up, frantically beeping, then rebooting.

After fishing for the card’s manual on the Interwebs, I could interpret the beeps and replace the bothersome component (RAM got fried IIRC).

So, my advice would be : get a 3 bucks buzzer :), there’s a good chance your MB is talking to you.

15

You have been told plenty. But did you require each claim to meet principles even taught in junior high science? If he says something without technical reasons why (based in well proven science) and without numbers (perspective), then it is probably a lie or urban myth.

Same urban myths also proved smoking cigarettes increase health. Over 60% of us knew that was true. Their feelings confirmed it. Then viciously attacked the Surgeon General for exposing that urban myth.

If any part is damaged by low voltage or power off, then quote spec numbers and datasheet facts that say so. No replies exist for one simple reason. Reality is found elsewhere. Not in feeling, hearsay, speculation, or claims made without numbers.

Power off sequences store unsaved data. Then hardware suffers a sudden power off. Makes no difference whether that power off is from an internal transistor cutoff, or a yanked plug, or a nuclear power plant shutdown. All are sudden power offs.

Again, an international design standard, that existed long before PCs even existed, says it in all capital letters: No Damage Region. Those standards even provided specific numbers. Unfortunately, too many believe a first thing told rather than learn how to separate lies from reality. Too many forget that answers without perspective (the numbers) and facts based in proven science is best called junk science.

Ignoring the challenge makes a conclusion obvious. Show me science, datasheets, or numbers that prove a sudden power off or low voltage is destructive to electronics. Nobody does for one simple reason. All power offs are sudden and not harmful.

Voltage can drop so low that incandescent bulbs dim to 50% intensity. Notice more numbers. Even that voltage is ideal and sufficient for all electronics as required by design standards and because of how electronics work. If voltage drops lower, then electronics simply power off - without harm.

Same concept applies to the OP. He is at wits ends due to speculation. By not “following the evidence”. A useful answer without speculation is possible in mintues. Provided if requested. Using a tool that actually ‘sees’ the defect. A defect must be identified before any solution is implemented. Then the solution is quick. And a reason for that defect is also learned. Doing this even shows why “sudden power offs does not cause electronic hardware damage”.

16

When I did not use battery back up, my computers would break. :mad:

My computers are not broke now. :smiley:

Why should I do anything different? :confused:

Hope the OP posts what he finally finds the problem is. I would really like to know. :cool:

17

Leaving aside the power outage…*

Since I can’t come up with anything else, I’ve ordered a new motherboard - an Asus H97i-PLUS. It should arrive today. I’ve also ordered an aftermarket cooler; as I’ll be moving the CPU around, I may as well put a new cooler on it. I haven’t used anything but the stock cooler before, but it looks straightforward enough.

I’ll try it out without reloading Windows, but I expect to have to do that as well.

*Actually, I agree with westom that a power outage, by itself, shouldn’t cause any physical damage to the components. It wouldn’t surprise me, though, if in the split-second before/after the power dropped, they’re wasn’t a surge or other instability that could have. I don’t know if that was a contributing factor; correlation is not necessarily causation.

18

Have you considered replacing the cmos battery? They use the same battery model as most watches (CR2032, iirc) so replacements are easy to find and should run around $1-2 at your local supermarket.

Also, IIRC, the power you receive immediately after an outage is full of spikes and drops as every electric device in an entire neighborhood draws startup level power simultaneously.

19

Thanks for the thought, dstarfire, but as the new motherboard and cooler* has arrived… :smiley:

I’ll be making the swap around shortly - see y’all on the other side!

*Criminey, this thing is massive! Glad the motherboard is oriented horizontally in this case.

20

You’re wrong.