Computer acting weird after power went out

[Trmi8120]

Last night I put my computer in sleep mode before I went to bed like I usually do. All was fine until the power went out for around 5 seconds. A bit annoying, but no biggie. It wasn’t until this morning when I went to turn my computer back on when stuff started acting weird. Usually when I turn my computer back on after the power goes out it turns on just fine, but this time some stuff happened. My monitor turned on, the Dell logo flashed, and then the monitor turned off. Tried everything to get it back on, but the only thing that worked was unplugging and replugging, but the same logo flash and shutdown occurred. For my computer, the custom lighting profiles on my mouse and kb turned on, but the lighting on my Pc stayed default. All the fans seemed to be spinning.

When I get home i’ll try investigating more, but for now I just want to see if anyone knows of anything I could do.

[Sup]

Seems like the power supply didn't make it.

can you list all the parts in your computer and how old your power supply is? You can also test by getting a good power supply and put it in your computer to see if it works fine then.

[Trmi8120]

**** then.

It was an HP omen prebuilt I got back during the tail end of the mining craze. It was around a year ago I think.

Specs were:
I7 8700
1x 16gb ddr4 2666
256gb nvme ssd
1tb hdd
Gtx 1060 3gb
500w 80+ broze psu

[yui]

either the power supply fried (maybe a bit under powered for that system) or the mother board thinks it is the power supply when really it is itself, or a device with a short somewhere (try unplugging stuff and see if it goes further or if you have a multi/voltmeter try measuring if you have 12V on the yellow and 5V on the red (black is ground) and there should be a power ready signal on the 24 pin connector (if there is one) maybe try to check that?)

[Trmi8120]

I’ll try this stuff when I get home. It might be beneficial to add that all the fans were spinning normally when I turned on the computer.

[yui]

well that would mean that you most likely at least have something on the 12V rails, does not say much of anything else sadly (fans can run on as low as 3V for some only run slower)

[Trmi8120]

Got home and messed around with thing. Unplugged various cables in my pc and to my surprise when I plugged everything back in my pc worked again, so I guess problem solved 

[dubious]

Why do you use sleep mode? IMHO weird stuff can happen with sleep mode and it's generally not worth it, especially if the computer loses power while trying to retain it's previous state. Just do a regular shutdown every night, your boot ups should be quick enough with an nvm-e drive.

[yui]

Got home and messed around with thing. Unplugged various cables in my pc and to my surprise when I plugged everything back in my pc worked again, so I guess problem solved 

Sometime a good complete power off (from the wall) can fix a lot of things, i did forget about that bit in my previous answer, some motherboard will not want to power back on after a power problem until you completely power them of ("modern" pc always have 5V power on the atx connector) and some power supplies do have similar system for overload protection, and sometimes a power cut that is just the wrong length can trigger them and not reset them.

[Leslieann]

It's a resettable fuse, many better power supplies,  have one.
Unplug it, press the power button a few times to drain the power, wait a minute or two for it to reset and they often come back to life after plugging things back in.
Sounds like what this one did.


By the way, if you are plugged into a power strip you hope to protect your system, replace it, it's fried. It may have saved your system, but it is now just an extension cord.

[yui]

By the way, if you are plugged into a power strip you hope to protect your system, replace it, it's fried. It may have saved your system, but it is now just an extension cord.

why would it have fried? it was just a short outage not a over voltage situation, and even in those cases it would require quite a big one to kill a surge protector, or were you talking uninterruptible power supply?

[Leslieann]

why would it have fried? it was just a short outage not a over voltage situation, and even in those cases it would require quite a big one to kill a surge protector, or were you talking uninterruptible power supply?

It surged when it came back on, why do you think the fuse tripped. The strip was also probably already blown before and just reset which is why it got through (or it is just junk in general).
Replace it, or be prepared to replace the PSU next time (if you are lucky that will be all that dies), your choice. You dodged a bullet.

Power strips are rated for how much surge they can handle, most are garbage. If you want real protection a strip should be rated at 1000 jules, or better yet get a lightning protected UPS (preferably with line conditioning). In either case, if it takes a hit enough to trip the system it's done.


Also, you never know where the surge will go, it can take out a tv in one room leave everything else untouched, trip the fuse on this system and touch nothing else... or it can go right through all of it and fry the hard drive or destroy nearly everything in the house. I've seen all of those, some more than once. I've even seen it pop capacitors off inside the power supply with enough force to dent the housing. Personally, if it gets to the power supply, the system needs to be monitored as it may be damaged, this goes double if the psu is dead. If it shows any sign of getting past that, the entire system is considered compromised and may as well just be replaced as a whole. You can try re-using parts from it, but usually ram and cpu are all that survive it it gets past the psu. Sometimes not even those.

Regardless, if you do everything or nothing, MAKE BACKUPS NOW to a system that was not plugged in.

[yui]

Surge protector protect against voltage surges, fuses (resetable included) protect against over current, a voltage surge may induce an over current (resistive loads) but so does a power outage as when the voltage goes low the switching power supply start drawing more current (the whole P=U*I as the power need to stay constant) and can trip it, and in integrated system it is more often a security on the motherboard in case it detects a low voltage on a line than in the psu, the psu often only gets a simple fuse.

Although you should always backup, better to have that small annoyance than to lose all your data at once.

And as for the surges, electricity will find the path of least resistance, so often will only take one thing out if it fails with a short (or an arc), or everything until something shorts it out

[suicidal_orange]

This technical stuff is very interesting, makes me wonder why most BIOSes have an option to power on after power outage though.  If the power supply is weird at that moment isn't that a really bad idea and the system would be safer powered off?

[Leslieann]

Surge protector protect against voltage surges, fuses (resetable included) protect against over current, a voltage surge may induce an over current (resistive loads) but so does a power outage as when the voltage goes low the switching power supply start drawing more current (the whole P=U*I as the power need to stay constant) and can trip it, and in integrated system it is more often a security on the motherboard in case it detects a low voltage on a line than in the psu, the psu often only gets a simple fuse.

Although you should always backup, better to have that small annoyance than to lose all your data at once.

And as for the surges, electricity will find the path of least resistance, so often will only take one thing out if it fails with a short (or an arc), or everything until something shorts it out

Good info, I hadn't thought about the swapping current for voltage.
I'd still replace the strip as it's cheap insurance.

This brings up a good point as well.
Low voltage/current is just as bad for computers as high current/voltage, it taxes the heck out of the capacitors which are there to buffer the lows. This has been a MAJOR problem for home routers for YEARS and is why so many of them fail after a year or so.