# PC often makes alarm like noise when powered on



## Sviatapolk (Jul 11, 2010)

I have an old Windows XP machine (p4 1.7ghrz) that more often than not won't power up.
What happens is that I push the button and after a few seconds it starts to make an alarm sound that sounds like British emergency vehicles (eeh ah eeh ah eeh ah).
When this doesn't happen it proceeds to make the usual startup beep and all proceeds normally.

I'm unable to replicate the error at will. Usually once a successful power up takes place I can reboot it dozens of times and it will always work. But then if I leave it for 24 hours it may happen again.

I thought it may be a monitor detection issue, but I've tried it with multiple monitors and once a successful boot has taken place, I can powe down unplug the monitor and still reboot it.

I'm pretty sure it's not a RAM issue.

Any ideas? Is it just an old PC dying a slow death?


----------



## makinu1der2 (Jan 1, 2008)

Post the specs of the PC. 

MB
CPU
RAM
GPU
PSU brand/wattage


----------



## Doby (Jan 17, 2006)

That siren is usually a cpu overheat warning so check that out maybe a good idea to clean and reapply thermal paste but they way you describe whats happening makes me think the the sensor is wacky


----------



## Sviatapolk (Jul 11, 2010)

makinu1der2 said:


> Post the specs of the PC.
> 
> MB
> CPU
> ...



It's a custom built computer I was given, I don't have the specs. Even looking inside I couldn't figure out the model of the MB.


----------



## Sviatapolk (Jul 11, 2010)

Doby said:


> That siren is usually a cpu overheat warning so check that out maybe a good idea to clean and reapply thermal paste but they way you describe whats happening makes me think the the sensor is wacky


If the sensor is wacky is there anyway to just shut it off?
I got the computer 1 1/2 ago and it's done this from the get go.


----------



## Doby (Jan 17, 2006)

Its possible by going into bios and disabling the cpu overheat protection *but I don't recommend this* because if there is a overheat issue this will save your system

First make sure the heatsink is clear of dust, use a can of compressed air to clean, then make sure the heatsink is tight, if the problem continues clean and reapply thermal paste its best to use artic silver5 and apply according to the directions on there website.

http://www.arcticsilver.com/instructions.htm


----------



## japong (Aug 13, 2008)

it could be an overheat issue try to change the processor fan also apply thermal paste, your processor fan could be failing.


----------



## hello_there (Jul 13, 2010)

It's not likely to be an overheating warning the second you boot the PC. Even without a CPU fan the heatsink will keep the CPU cool enough without it for a bit. It's likely to be a "fan not working" warning and if the PC won't boot because of it, it's more likely to be the CPU fan.

Open the side of the case and have a look to see which fan isn't working when it happens. The fan's probably getting old and not spinning up easily, or it's clogged up with dust.

You can probably disable the alarm in the BIOS and the fan will start spinning when the CPU warms up a bit and the motherboard responds by giving the fan a little more power to spin it faster. If that's what's happening it's fairly safe to use the PC that way because if the fan stops working while the PC is running the alarm will sound again, but it's probably best to fix the problem.


----------



## hello_there (Jul 13, 2010)

Sviatapolk said:


> I'm unable to replicate the error at will. Usually once a successful power up takes place I can reboot it dozens of times and it will always work. But then if I leave it for 24 hours it may happen again.


That definitely says "fan" to me. When the fan is cold it doesn't spin up as easily as when it's warm, and/or, because the CPU is already warm after the first boot the motherboard gives the fan more juice on subsequent boots due to the CPU temperature being higher than it was when you first tried to boot the PC "cold".

A second thought.... rather than disable the fan warning you could disable the CPU fan speed control in the BIOS. That'd get the motherboard trying to spin the fan at full speed right from the start, but it could also make the PC somewhat noisy.


----------



## Sviatapolk (Jul 11, 2010)

hello_there said:


> That definitely says "fan" to me. When the fan is cold it doesn't spin up as easily as when it's warm, and/or, because the CPU is already warm after the first boot the motherboard gives the fan more juice on subsequent boots due to the CPU temperature being higher than it was when you first tried to boot the PC "cold".
> 
> A second thought.... rather than disable the fan warning you could disable the CPU fan speed control in the BIOS. That'd get the motherboard trying to spin the fan at full speed right from the start, but it could also make the PC somewhat noisy.


Thanks. This seems to make sense. Yesterday I tried an experiment - usually when it happens, I immediately shut it off and then try again. It could go like this 12 times.
But yesterday I turned it on and I let the alarm go for a few minutes. Then I shut it off, tried again, andit booted right up. So I suspect that there is a delay in a fan starting when it is "cold," and that this isn't an overheating issue (again, once it's on I can leave it on for days with no problems).

I'll try your suggestions later and see if they help.


----------



## Doby (Jan 17, 2006)

The fan is certainly a good point Worth watching and you should be able to tell simply by watching it at startup, problem is all boards that I know of warn by giving a message at startup about cpu fan failure and the siren sound is only made when the board senses a cpu overheat not a fan failure thats why I said about a wacky sensor or something just ain't right.

If we knew the motherboard we could look for similar issues, still though its good to cover all the bases and clean and reapply thermal paste and even replace the fan and/or heatsink


----------

