Old laptop makes funny noise when CPU is under load

[Jeff7]

I assume there's nothing to be done about this, and it's probably just coil whine, but still, it's weird. Maybe someone will find it interesting or know something to do about it.

Situation: I replaced the P3 600MHz processor in a Presario 1700 17XL360 laptop with an 850MHz processor. I started running Prime95, and within a few seconds, it starts making a funny noise, except for the Small FFT Torture Test - no noise then. It's primarily high pitched, centered around 10,500Hz, but there are also some components around 5,000Hz and 1,400Hz. It also looks like the three main frequencies take turns. It's not in an exact alternating pattern, but when one of those three frequencies is sounding off, the others are quiet.

Filtered audio sample (MP3, 473KB)

Audiograph

Thus far it seems to be running Prime95 just fine.

 

[Aarondeep]

Does the problem occur only when plugged in? Can you replicate the issue when you are just using the battery?

 

[Jeff7]

It does it when on the battery too, but it's just ever so slightly quieter. No change in pitch or frequency.

 

[Tsaico]

Sounds alot like a sleeve bearing fan that I had and died on me. The fan's grease pack was gone and the metal was rubbing on itself, even thoug it still spun. Made a high pitch sound like that too. (though mine was right away) If it were a fan bearing, then the CPU under load bring up the heat, so the fan kicks in at that point, when otherwise it just sits there.

Good luck though, if it isn't a fan, I have no idea.

 

[Jeff7]

Certainly not a fan - most of the time, no fans are running at all.

The way the sound coincides perfectly with CPU activity indicates that it isn't a fan - fans are thermally controlled, and it takes a little bit for CPU activity to translate into a temperature change. With Prime 95, it stops immediately when I end the torture test.

It also changes with differences in the kind of CPU activity.
Frequency shift when dragging a window

Audiograph

Right around 1 second, I started dragging the Sound Recorder window around. This changed the squeaking. Then about 0.75s from the end, I stop the Prime95 test. The squeaking stops immediately.

 

[Tiamat]

That happens with my brand new Dell e1505. Its most likely coil whine. I havent had the time to ask dell about it.

 

[Aarondeep]

Taken from HP's Support Web-Site:

DESCRIPTION
A high pitched or buzzing sound may occur when using the notebook PC.

"This is normal behavior when the notebook PC is used in certain power configurations. Under certain power connfigurations the power supply capacitors in the notebook can resonate, producing an audible sound."

SOLUTION
Reduce the sound by selecting a different power scheme.
You can adjust power configurations through Start > Control Panel > Power Options. Power saving schemes such as Portable/Laptop and Max Battery yield the best results.

-----------------------------------------------------------

ISSUE:
The AC Adapter of the HP or Compaq Notebook PC makes a hissing, and/or crackling noise and may feel warm to the touch.
This is more prevalent after the adapter has been connected to AC power for a period of time.

SOLUTION:
AC Power adapters do emit high frequency sounds (15 kHz-20 kHz) that may be misunderstood as hissing or crackling noise. This is normal and not an indication of a failing adapter.
The temperature of the adapter also may feel warm to the touch. This is normal operation too

 

[Jeff7]

Interesting solutions from HP.

Makes me wonder if selecting a different power scheme might make the CPU throttle down, thus decreasing the load on the power supply? Sort of like when some companies say "Lower hardware acceleration to make our software work" - which effectively disables most of the hardware's capabilities.

The other one, that this is a "normal" sound - this is a very noticeable sound. It's not just some near silent thing - I can hear it from more than 10ft from the laptop, with a moderately noisy PC only 2ft from my head.

However, one thing caught my eye - "capacitors." When did that whole bad caps fiasco break out in Taiwan? Maybe I'll have to open this thing up and look for bulging caps...but then, notebooks might tend to use those aluminum electrolytic capacitors, and I don't know if they do bulge in the first place.