# Hard drive "pulsing" noise



## RoddyC (Jan 8, 2006)

Yesterday I purchased and installed a Maxtor DiamondMax10 300GB SATA drive. I installed it as a second hard drive for data storage only. However now my computer is making a strange noise.

The noise is constant, no matter what tasks are being performed. It happens immediately from turning on the computer. I would describe it as being a "pulsing" sound. I hear 3 seconds of low noise, then it fades out to silence for about 3 seconds, then the noise picks up again for 3 seconds, etc etc. And this happens constantly even when the computer is idle. There is no difference in the noise when the drive is being accessed. 

I don't know if the noise is coming directly from the drive, or from a fan or something, but the noise IS directly CAUSED by the drive. I opened up my computer and disconnected the drive's power and interface cables, and the noise immediately went away. But I left the drive in place, so the noise is not caused by something vibrating against the drive - it only happens when the drive is powered. 

Thanks in advance for your help in resolving this issue. :up: 

Oh yeah, I should try to post some of my specs:

Alienware Area-51 7500
Dual-core P4 3.0GHz
1GB RAM
Primary drive - 160GB SATA
WinXP Home SP2

I'll be happy to answer questions if more info is needed.


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## JohnWill (Oct 19, 2002)

That sounds a lot like bad bearings in the drive. However, it's remotely possible that you are hearing a beat frequency between the two drives. Does unplugging the other one and turning the system on change the sound?


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## Noyb (May 25, 2005)

Sounds like a Beat note ... I'm wondering what it would sound like - if you unbolted it from the case and let it hang loose for a test.

Can you return it for another ?


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## bigbear (Apr 27, 2004)

It should not be making that noise, I assume it securely mounted? Try taking a something like a wooden spoon and place one end on the hard drive and the other end to your ear and see if you can isolate the noise, if it is coming from within the drive I would take it back and get a replacement


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## Noyb (May 25, 2005)

If it's the beat difference in the RPMs of the two drives - then the sound may be coming from the mounting case as well.
I'm thinking for this to happen - both drives would have to be out of balance .. or beyond specs.


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## RoddyC (Jan 8, 2006)

After some testing, I'm pretty sure the drive isn't bad. I took it out of its mounting and placed it standing up vertically against the side of the case. When I booted up, the noise was gone as far as I could tell. But I can't leave it in this position - it would be likely to fall over. And the only available mounting brackets are in a row directly under the primary drive. Any ideas? I tried mounting the drive in a lower bracket, and then in the _lowest_ bracket. But the noise problem remained.

Another thing I have noticed is that the noise does indeed resonate through the casing. If I put pressure on certain parts of the casing, especially near the front (close to the drive) then I can somewhat muffle the noise.

If it should be the case that the drives are out of sync with each other, what can I do? Is there some way to slow down one, or speed up the other? That seems like a likely explanation to me, but I'm not an expert.


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## jflan (Jun 27, 2005)

If it were me and the sound was unbearable I would exchange the drive for a quieter one, such as a Seagate or Samsung Spinpoint.


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## RoddyC (Jan 8, 2006)

Some more info:

The primary drive is a Hitachi Deskstar 7K250, 160GB, SATA-150, 8MB buffer, 7200RPM.

The secondary drive is a Maxtor DiamondMax 10, 300GB, SATA-150, 16MB buffer, 7200RPM.

I would guess the difference in buffer size is insignificant. But according to these specs they should both be spinning at the same speed.


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## JohnWill (Oct 19, 2002)

Well, "spinning at the same speed" is a relative term. I doubt that either spin at exactly 7200 RPM.  It doesn't take much difference to have a low frequency "beat" frequency. That's why airplanes, especially multi-engine prop planes, have a little indicator to tell you the difference between the engine speeds. Just a few RPM's generates a really annoying beat frequency!


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## Noyb (May 25, 2005)

Before going any farther with modifying the mounting - can you replace/exchange the drive.
It really shouldn't be that far out of balance.

I'm running twin Western Digitals SATAs hard mounted right beside each other - no noise at all.


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## RoddyC (Jan 8, 2006)

I'm not ready to exchange it just yet. I'm hoping I can figure out a solution.

I moved things around and re-mounted the drive. When I booted up I had almost no noise. But then I played Civilization 4 for a few hours (an act which sent my GPU reported temperature from 60 to 80 degrees C) and the noise returned. As I was playing, the pulsing/throbbing from the drive became progressively faster, which made me think the rising temperature inside the box was somehow related. It peaked around 80C (reported from the graphics card) as it usually does, and by this point the pulsing was around 2 "beats" per second. I would describe the starting noise as 1 beat per 4 seconds. 

So I quit out of the game and returned to the desktop. I watched as the temperature reading fell back to idle levels, and with that the noise subsided. 

I'm thinking about putting a couple of extra fans in there to keep the temps in the 60s and below. But I don't fully understand the relationship between the noise and the changing temps. So I'm unsure if that would solve anything.


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## kiwiguy (Aug 17, 2003)

The drive speed(s) may vary a few RPM with changing temperature, and with it will change the difference between the drive speeds and the resultant low frequency "beat" which is that difference.

I would have serious concerns about both drives in that they should not have sufficient vibration to even cause a differential "beat" that is audible.

If one drive spins at 7,215 RPM and the other at 7,185 RPM that is a beat of ~ 2 seconds.


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## jflan (Jun 27, 2005)

I like that multi-engine airplane analogy or a multi-engine boat...to my ear it's a drone, a pulsating drone. 

Now that you mention heat, I'm thinking that if that is so, then somehow the internal clearances in that drive may be out of whack. Heat > expansion > and so on.

An easy way to see if your cooling is not adequate is to open your case and point a common house fan at it. Then light up your comp, mash the throttle and see what the temps do.

If you can get it to run at a cooler temp, then it's possible that you can duplicate that with some fan adds or changes.


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## qldit (Mar 18, 2005)

Good Evening Gentlemen, that drive sounds like is is ready for the happy hunting ground. I cant imagine any beat causing that effect without having a major inherent problem. My DC-4 used to have three little propellers in an indicator for "fine trimming" the throttles. My L-188 was auto-synchronised. It sure beat the beat!
qldit.


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## Noyb (May 25, 2005)

Just some numbers for you 
An out of balance hard drive, spinning at 7200 RPM will produce a sound of 120 Hz (cycles per second)
Anytime two sounds are mixed  four sounds are produced including the sum and difference of the original two.

You originally said you heard the beat for 3 seconds followed by 3 seconds of quiet.
This would be a 6 second cycle .. or a frequency of .167 Hz  which is the difference between the two hard drive speeds 
equating to about 10 RPM difference  in the 7200 RPM speeds.
Since this PRM is controlled by the circuitry in the HD - I would expect this to change with temperature.

What you are probably hearing is this .167 Hz difference Beat frequency modulated by the 120 Hz (or the sum of the two frequencies) = 240hz  or any harmonic of 120 Hz  Depending on any case resonance frequency.

Simply stated ... The problem is that the HDs are producing noise in the first place 
Or you case is naturally resonate at 120Hz which will amplify the HD vibration and create the Beat Frequency.
The Simple answer is  get a quiet HD that isnt vibrating as bad.
It takes Two to Tango.


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## JohnWill (Oct 19, 2002)

Did you ever unplug the other HD to see if it is indeed a beat frequency between the two?


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