My main old desktop started acting odd yesterday. Something is broken, not sure which part. I built the system several years ago. It has an Antec Lanboy case, Antec Smart Power PS, Biostar mb...
The rear exhaust fan has blue LED lights, which I can see through the large side window in the case. After powering down/shutting off the system the other day, I noticed the rear fan made several popping sounds & lit up for a second, repeatedly for about a minute or 2 after the tower shut off.
Then this morning I saw it doing the same thing, before I even turned the system on, it had been off for over 12 hrs. It is plugged into a power strip which was left on. This freaked me out & I shut off the power strip.
When I turned on the power strip several hours later, the computer turned itself on without me needing to push the power button. It now won't power down.
So is the problem a broken switch on the MB? A bad power supply? Bad switch on the case? Something else entirely?
I plan to shut off the power strip it is connected to as a safety precaution, but I'm concerned about a possible fire, or is that being paranoid?
I have always powered it off/shut it down when not in use.
What should I do? Fix? Replace?
Thanks for any & all advice.
Full Version: Computer power weirdness, help very much appreciated
Wow, I'd love for Alan to jump in here, but it's clear that something is very wrong. There's definitely some sort of power issue, but I don't know whether it's coming through the motherboard, or if the power supply is shot. There's really no way to know without replacing it and re-testing I would think. Do you have another PS around?
I don't think you are being paranoid about a fire hazard.
I don't think you are being paranoid about a fire hazard.
Somewhere I have an extra brand x power supply [from an ancient free after rebate Compusa deal] that I could use if that might be the problem.
I always bought cases with installed power supplies, but it can't be that difficult to swap in a new one, if that is the problem. Never had a ps go bad on me before.
I always bought cases with installed power supplies, but it can't be that difficult to swap in a new one, if that is the problem. Never had a ps go bad on me before.
Power supplies go bad more often that you'd think, especially those manufactured during the problem period with defective capacitors a few years ago.
Which brings up a good point - defective capacitors. Before you do anything, carefully look over the motherboard and see if you can find any swelled or leaking capacitors as it sounds like this motherboard might be old enough to have been built during that period. If you find any, you don't need to look any further. The following site has some pictures (on the right side of the screen) as examples of what to look for:
http://www.badcaps.net/pages.php?vid=5
Absent obvious swelled or leaking capacitors, I'd check in-order as follows: case switch, power supply, grounding issues, and motherboard swap.
To eliminate the case switch as the source of the problem, you can remove the case switch lead from its jumpers from the motherboard and use a flat screwdriver to start the computer by carefully (i.e. making sure not to touch anything else) shorting the switch pins -- case switches are normally just momentary switches, so just touching the leads should be enough to start it. I'd run it a few minutes, then shut it down from the OS. If the computer continues to misbehave without the case switch attached, you can obviously eliminate that as a source of the issue.
Switching the power supply would definitely be the next step - just make sure that the old supply you are swapping in is rated at enough wattage to run everything you have installed in your computer (especially if you have a higher end video card). Swapping it out won't be hard, though it may be time consuming.
If it still happens at this point with the new power supply, I'd make a cursory check to ensure that the motherboard is properly mounted to the case and that nothing is accidentally grounding out. If not, then you can probably then assume the motherboard is bad.
Which brings up a good point - defective capacitors. Before you do anything, carefully look over the motherboard and see if you can find any swelled or leaking capacitors as it sounds like this motherboard might be old enough to have been built during that period. If you find any, you don't need to look any further. The following site has some pictures (on the right side of the screen) as examples of what to look for:
http://www.badcaps.net/pages.php?vid=5
Absent obvious swelled or leaking capacitors, I'd check in-order as follows: case switch, power supply, grounding issues, and motherboard swap.
To eliminate the case switch as the source of the problem, you can remove the case switch lead from its jumpers from the motherboard and use a flat screwdriver to start the computer by carefully (i.e. making sure not to touch anything else) shorting the switch pins -- case switches are normally just momentary switches, so just touching the leads should be enough to start it. I'd run it a few minutes, then shut it down from the OS. If the computer continues to misbehave without the case switch attached, you can obviously eliminate that as a source of the issue.
Switching the power supply would definitely be the next step - just make sure that the old supply you are swapping in is rated at enough wattage to run everything you have installed in your computer (especially if you have a higher end video card). Swapping it out won't be hard, though it may be time consuming.
If it still happens at this point with the new power supply, I'd make a cursory check to ensure that the motherboard is properly mounted to the case and that nothing is accidentally grounding out. If not, then you can probably then assume the motherboard is bad.
QUOTE (steltek @ 2-2-11, 7:16am) 
Power supplies go bad more often that you'd think, especially those manufactured during the problem period with defective capacitors a few years ago.
Which brings up a good point - defective capacitors. Before you do anything, carefully look over the motherboard and see if you can find any swelled or leaking capacitors as it sounds like this motherboard might be old enough to have been built during that period. If you find any, you don't need to look any further. The following site has some pictures (on the right side of the screen) as examples of what to look for:
http://www.badcaps.net/pages.php?vid=5
Absent obvious swelled or leaking capacitors, I'd check in-order as follows: case switch, power supply, grounding issues, and motherboard swap.
To eliminate the case switch as the source of the problem, you can remove the case switch lead from its jumpers from the motherboard and use a flat screwdriver to start the computer by carefully (i.e. making sure not to touch anything else) shorting the switch pins -- case switches are normally just momentary switches, so just touching the leads should be enough to start it. I'd run it a few minutes, then shut it down from the OS. If the computer continues to misbehave without the case switch attached, you can obviously eliminate that as a source of the issue.
Switching the power supply would definitely be the next step - just make sure that the old supply you are swapping in is rated at enough wattage to run everything you have installed in your computer (especially if you have a higher end video card). Swapping it out won't be hard, though it may be time consuming.
If it still happens at this point with the new power supply, I'd make a cursory check to ensure that the motherboard is properly mounted to the case and that nothing is accidentally grounding out. If not, then you can probably then assume the motherboard is bad.
Which brings up a good point - defective capacitors. Before you do anything, carefully look over the motherboard and see if you can find any swelled or leaking capacitors as it sounds like this motherboard might be old enough to have been built during that period. If you find any, you don't need to look any further. The following site has some pictures (on the right side of the screen) as examples of what to look for:
http://www.badcaps.net/pages.php?vid=5
Absent obvious swelled or leaking capacitors, I'd check in-order as follows: case switch, power supply, grounding issues, and motherboard swap.
To eliminate the case switch as the source of the problem, you can remove the case switch lead from its jumpers from the motherboard and use a flat screwdriver to start the computer by carefully (i.e. making sure not to touch anything else) shorting the switch pins -- case switches are normally just momentary switches, so just touching the leads should be enough to start it. I'd run it a few minutes, then shut it down from the OS. If the computer continues to misbehave without the case switch attached, you can obviously eliminate that as a source of the issue.
Switching the power supply would definitely be the next step - just make sure that the old supply you are swapping in is rated at enough wattage to run everything you have installed in your computer (especially if you have a higher end video card). Swapping it out won't be hard, though it may be time consuming.
If it still happens at this point with the new power supply, I'd make a cursory check to ensure that the motherboard is properly mounted to the case and that nothing is accidentally grounding out. If not, then you can probably then assume the motherboard is bad.
Thank you!
I've seen many systems that will power on (and won't turn off) as soon as they're plugged in. In most cases it's a power supply issue. In other cases it's the power switch. I personally have never seen this behavior with a bad motherboard, however I have seen power supplies damage motherboards.
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