14 replies to this topic

[Brew Man]

Hey,

PC is starting up by itself,if you connect to internet it shuts down by itself in awhile.If you start pc and connect it stays on like it should, till you sign off and shut down.Anyone know whats up,it's also running pretty slow.

 

[Brew Man]

Hey,

Computer is starting to shut down when you are usung it. I figured the added info might help.

[Samurai Appliance Repair Man]

May be a flakey power supply-- I've had this problem on several PCs. Or could be a virus in your PC. I'll tell you the same thing Microsleaze tech support will tell you: re-install the operating system. Doesn't that suck? That's why I went Mac two years ago and haven't looked back. Leaving the Windoze world and going to Macs was like breaking out of jail.

[rofiguer]

If your system is connected to the Internet via an ethernet cable you may want to check to see if the "Wake On LAN" feature is enabled in the BIOS. This is an advanced feature that will allow a System/Network Admin to turn machines on and off for remote maintenance.  This feature can also be used to by hackers to gain access to a machine, so its best to have this feature disabled if not needed (most home users will not need it). In your case, if it is indeed connected to some network the  system may just be getting some random system causing it to "wake up" (a few years back several updates were released to correct this problem for multiple PC manufacturers).  This can be done from the advanced settings in the BIOS. Different systems have different ways to access the BIOS, so you'll have to bring out that owners manual to see how to access yours (if you provide the type of computer we can look that up). Disable it and see if the problem persists.

[pmik]

Sensei Samurai is probably correct.

A bad power supply will do exactly what you describe.

Replace it and all will likely be well.

Make sure you get exactly the same voltage/wattage/ and Amps or you will fry the motherboard.

Power supplies are fairly cheap,probably around $40.

Also, please use at least a surge protector to protect against transient voltage and current variations which can ultimately fry or slowly destroy a power supply.If you get an inexpensive UPS[uniterruptible power supply] which is basically a battery that plugs into the wall and your computer plugs into the UPS, it *may* also condition the power to eliminate or reduce high/low voltages.APC is a brand that is reliable for example.Most office supply stores carry UPS.

I live high in the Sierra Nevada and our utility supplied is power is horrible.It has high and low voltages like you wouldn't believe, and this wreaks havoc on the my network and the many computers I manage for a local town.Everything goes through at least a conditioner/ surge protector or UPS.

arigato and gokouun o inorimasu

 

[Samurai Appliance Repair Man]

Hey, Patrick, nice pictures on your home page and contact page.

[Keinokuorma]

[user=25682]pmik[/user] wrote:

Sensei Samurai is probably correct.

Most likely yes, I suspect the PSU too.

If it does that with the network cable detached, it is unlikely to be the WOL function. Which is mostly useless anyway. Either disable if from the Setup menu, or remove the wire from between the LAN and mobo, or turn the jumper off on the mobo, whatever the method. If the computer turns on on its own volition even then, I suspect the PSU first. 7 of 10 cases in my history have been solved with new PSU, the rest mostly had flaky capacitors on the mobo.

Make sure you get exactly the same voltage/wattage/ and Amps or you will fry the motherboard.

Input voltage from the mains must match, yes, but most PSU's are now international and rather omnivorous, will run off of 120ish ar 240ish Volt systems regardless of frequency... mostly with a hand set switch, but some newer ones work with anything between those (or closely around) without user intervention.

Otherwise, as long as the voltages for the mobo are correct and there is enough reserve wattage output, the system will take care of the amperes. You can wire a new 600W supply to an old P200 motherboard, and it will probably work just fine, while you can't run a modern system off of the 175W supply from the old P200.

Even if the modern system consumed no more than 150W mean power, it will draw peak load which will far more than exceed the capacity of the old supply. The 175W supply is thus more likely to blow the new mobo, than the 600W one to blow the old board. If the secondary circuit FETs give way, you may  be feeding 24 to 60V to the 12 and 5V inputs (yes the PSU chops such a high voltage to a low voltage, by PWM, producing RMS 12V and 5V voltages etc).

Matching the supply too closely to the mean power of the system is one reason why they go bad. Even if they survived the peak load for a year or two, maybe even five, the underrated semiconducotrs as well as other parts will grow old. They no more switch as swift, no more pass as much current, or hold as much voltage back. They will eventually get smoked if constantly maxed out. It is better to have reserve than shortage.

If you get an inexpensive UPS ... it *may* also condition the power to eliminate or reduce high/low voltages. APC is a brand that is reliable for example.Most office supply stores carry UPS.

Good advice there. Most UPS devices contain a surge protector wired in BEFORE the battery backup circuitry anyway, and most now have also outlets that bypass the battery but are surge protected. Good for connecting a laser printer or such high peak load device that the backup can't deal with. BUT, no good for connecting a coffee maker and vacuum cleaner like a friend of mine did. D'OH!

Note though, like you said, they *MAY* condition the power. Some of the cheapest UPS devices will not produce very pure power at all times. A pure sine wave output from battery backup would require a more sophisticated and expensive circuit than the usual, which produces "modified sine wave". That is technically some 70 to 75 per cent wide bipolar pulse wave at the nominal peak voltage of the power network. This would give out RMS voltage roughly the same as the sinus wave of the network, and thus be sufficient for the modern omnivorous PSU. You may encounter trouble with highly inductive loads employing a conventional transformer, induction motor, or fluorescent light etc. However the PC PSU is a capacitive load and will compensate the parallel inductive loads to an extent.

[Brew Man]

Hey,

Thanks for the input everyone,I'll let you know what happens.When the power supply was mentioned I thought you were talking about the surge protector.

[ether.real]

A bad PSU will explain the random power offs but not the random power ons.  WOL might explain the random power on, however this usually not enabled by default, especially on an OEM system like Gateway. 

Because he has both issues, I wonder if it is a bad power switch on the case.  It is rare for one to go bad, but it does fit the symptoms. 

So, here is a question for the OP:

When it powers off, does it shut straight off, or does it go through the shutdown sequence?

[Keinokuorma]

A bad PSU can cause spontaneus power-ons, sometimes partial so that all of the sudden you have 12V but no 3.3 or 5V, etc... I had one that did this. Changing the PSU solved the problem, I certified by plugging the old one to another motherboard, where it did the same thing.

[ether.real]

In all my years of PC repair, I have not seen one do this, so I would say its a pretty rare occurance.  In order for the PSU to randomly power on, the 5VSB rail would have to be intermittently shorting to ground somewhere.  Not impossible, but unlikely. 

[diamondsol]

The turning off sounds PSU the turning on is a mystery.
Some events are able to engage this kind of boot and all are managed by the BIOS. Mainly they are: Wake Up On LAN, Wake Up On Modem/IRQ Activity, Wake Up on USB, Wake Up On Alarm. If they are all set to disable the 5v rail seems a possibility however slim. PSU again.

[Keinokuorma]

Some months ago I had a case that seems to track back to WOL, but there was no means to turn it off. Don't remember the mobo model any more, but tere was no option in the setup, no jumper on the mobo... integrated network adapter, no wires either. The only jumper was for resetting setup, tried that too, but the problem didn't go away. It stayed in check by removing the lan cable for nights and the owner said it's OK like that... if I'm called back I will install a separate lan card, disable the integrated adapter, and see if it does the trick. If not, I'll have a known-to-be-good psu handy for the trip too.

Not necessary for 5vsb or pwron line to ground out to start the psu accidentally... could be a flaky control chip in the psu, gets power from the 5vsb line and waits pwron state to go low... might get cranky by age, of course could be fooled by fluctuations in 5vsb... unstable 7805 regulator... also some units use a separate iron core transformer and rectifier to feed the 7805, some do it through the main switching mode transformer... this difference may affect their longevity.

[obrien1984]

Dude,

Are you sure that it's shutting down and not just going into sleep mode? Do you get the "Windows Shutdown" screen (assuming you're running Windows)?

I'm going to part with the pack and suggest that your computer has a virus or worm. One of my computers at work started exhibiting really bizarre shutdown behavior. Turns out that it had a nasty virus, which damaged some of the system files. This still doesn't explain why it randomly turns on when it's just sitting there all by itself (unless, of course, it didn't really shut down in the first place).

Any thoughts?

Joseph

[Keinokuorma]

It also turns on of its own volition.