Noise from PC on booting up

[willowman]

The last couple of days my PC has given out a loud buzzing/vibrating noise on booting up.
If I switch off straight away and restart the noise is still there, but if I let the machine continue to boot up then the noise stops after about 2 minutes, and it's OK for the rest of the day.
Has anyone got any idea as to what it might be please?

[ChuckFickens]

open it up and clean the dust from all the fans, if that doesn't cure it then you have a fan going faulty (bearings wear out) and it needs replacing.

[willowman]

Thanks for the speedy reply Chuck.
Had a horrible thought that it may be the hard drive going t**s up.
Not that I would know what that sounded like anyway.

[willowman]

Been cogitating over your answer chuck.
Surely if the fan bearings were going then the noise would continue during the day as the computer warmed up and the fan kicked in?

[ChuckFickens]

Pretty much all modern computers have variable speed fans that speed up and slow down based on the load the computer is under (therefore the temperature the systems is running at) during normal use the fans will probably only be running at about 1/3 of their full speed. if you were to start running very CPU intensive applications on your computer you would probably find the noise would return as the fans speed up.

What the fans on a lot of systems do when the computer is turned on is run at full speed for a short time until the software that controls their speed has loaded, which is what you are hearing.

The easy was to tell is to take the side/top of the computer when it's switched off and simply stop the fan from turning with your finger as you turn it on (it will be fine with no fan running for a few minutes) and see if that stops the noise (and also see if the noise returns if you remove your finger from the fan)

[Prudie]

It's not something silly like you've left a CD in the drive is it? No....well just a thought

[willowman]

Thanks guys.
Just checked - no Cd in drive but worth a look.
Chuck - I'm one of those peeps who can strip down an engine, no problem, but suggest I open a computer and I'm filled with dread. So many stories in the early days that you mustn't touch this or do that etc.
But will try to extricate it from the desk (means crawling underneath the desk and unplugging most things, not easy at my age) and give your idea a go.
Certainly cheaper than getting our tame computer chappie in to see to it.
Will let you know the result.