Very Noisy PC - Why?

  jomuir 11:25 06 Jun 2006

I have got hold of an old pc (new to me, obsolette from my wifes work).

It has always been really noisy and I am presuming it is the fan working over time so was thinking of replacing it - I have added a second hard drive and upgraded the memory. I will list the spec below as well as temps and any help/advice would be looks like there are 3 fans, so not sure which one I will need to replace (is it a case of opening the box and listening to each one?)

Windows XP Pro
P4 3GHz (Prescott)
2 x 512MB
Intergrated graphics card (do not play games)

From PC Wizrd 2005:-
Chassis Fan 4440rpm
Processor Fan 661rpm
Power/Aux Fan 11250 rpm
Proc Temp 34C
Mainboard temp 25C
Power/Aux Temp 43C
80GB harddrive 45C
120GB hardrive 46C

  Gongoozler 11:42 06 Jun 2006

Hi jomuir. When you say that the fan is noisy, are you referring to the sound of air turbulance or to bearing noise?

A computer generally has 3 fans, sometimes 4. There is a fan in the PSU and one on the processor heatsink Modern graphics cards generally have a cooling fan and some motherboards have a fan on one of the chips.

The most common fans to develop bearing noise are the processor fan and motherboard fan. The easiest way to find which fan is making the noise is to take the side cover off the computer, then roll a sheet of A4 paper into a long tube and with one end against your ear use it to locate the noise source. The best way to deal with the problem depends on which fan is making the noise and whether it's air turbulance or bearing noise.

  Totally-braindead 11:45 06 Jun 2006

If the noise is fairly constant, ie there all the time, then I would think the easiest way to check would be disconnect the case fan and see if the noise disappears.
The other possabilities for noise are the CPU fan, the Northbridge fan and possibly the hard drive. I wouldn't really recommend disconnecting them for any length of time as with heat build up you could end up destroying the Northbridge or the CPU.
What I have seen people recommending is using a tube of paper or card pushed near to the fans one at a time to try to determine which one is noisy. Obviously while doing this do try to ensure you don't touch the fan.
I've had 2 boards with Northbridge fan failures so if the case fan is ok I'd check that one first.

  Belatucadrus 12:32 06 Jun 2006

I find the data from PC Wizrd on the CPU a little odd, a fan speed of only 661rpm on a P4 running as low as 34 degrees C, is so good I'd question it. That would require a huge heatsink and a pretty big fan to achieve. I concur with the others, a physical check is what you need next, and the paper tube is a tried and tested approach that works as well as anything.

I'd love to know what applications you wifes work was using that render a 3Ghz P4 obsolete.

  keef66 12:48 06 Jun 2006

If the psu fan is truly rotating at 11250 rpm it must be making a racket like a hairdryer.

Case fan at 4440 rpm is normal, but you can buy slower, bigger and hence quieter ones cheaply.

CPU fan at 661 rpm / CPU temp 34c??? One of these readings is wrong. Have you missed a 0 off the end of the rpm figure? A 6600 rpm fan on a decent cooler would probably keep a P4 at 34c, but it too would be making quite a noise.
Again you can get much quieter fan / heatsink combinations for a P4 without spending too much.

Does your wife's work have any more of those obsolete P4's available cos I'd quite like one.

  jomuir 14:54 06 Jun 2006

yes, I also thought it was to good to be true (spec wise) and no they only had 2 they where getting ride of and kept the rest.

I have just check the values again and they have remained the same except for the mainboard now 51C.

So going by this it could be the processor fan as it is going far to slow, or the psu fan as it is going too fast.....

I have just installed Everest Home Edition and its figures are different:-
Motherboard 52C
hardrives both 46

Chassis fan 4327rpm
Power Supply 2812rpm

looks like I will open the box, give it a clean and listen with the paper.

  Gongoozler 14:58 06 Jun 2006

A very good program for monitoring temperatures in real time is MBM5 click here

  Belatucadrus 15:11 06 Jun 2006

I'm more inclined to trust the Everest figures than those provided by PC Wizrd. They look more in line with what I'd expect, with one exception I think that the MOBO temp looks a touch high. First point of call is probably to check the Northbridge fan.

  keef66 15:53 06 Jun 2006

If it is the NB fan, replace it with a passive heatsink; Zalman do a selection. Absolute silence and maintenance free!

My mobo has passive NB cooling and I'm grateful

  Gongoozler 16:19 06 Jun 2006

If you do replace the chipset fan, this is probably what you need click here

  Belatucadrus 16:39 06 Jun 2006

click here Link for the Zalman passive northbridge heatsink.

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