Acoustics

Our acoustic test utilizes our standard test bed components but we implement Intel's power saving technology and turn off the case fans to eliminate as much case noise as possible during testing. Our Corsair power supply is nearly silent in these tests and our MSI 8800GTX video card is water cooled by an external pump/radiator unit to provide a further decrease in our case's ambient noise levels. Our drives are attached to the drive cage with rubber bushings to assist in isolating the noise of the drive and avoid the resulting harmonic changes due to the case design.

Our acoustic tests are designed to measure the decibel levels while the system is at idle and also under load while running the General Hard Disk Drive Usage benchmark within PCMark 2005. We found through trial and error that this particular benchmark produces controlled readings across a wide range of applications within the benchmark. This particular benchmark utilizes 60% reads and 40% writes within the trace playback file.

The measurements are taken at a distance of 5mm from the rear and front of the drive being tested in order to minimize surrounding environmental noise. We have noticed that unless we run a completely silent system in a quiet room that measurements taken from 1m are generally not meaningful because they are lost in the surrounding ambient noise. There are exceptions - like the Raptor series of drives - but overall most modern desktop drives are quieter now than the other components in the system.

The reported measurements are based on an A-weighted decibel score that measures frequencies similar to the way the human ear responds to sound. We take a total of three measurements for each test. We then subtract the high and low scores and arrive at our findings by reporting the remaining score. Our base dB(A) level in the room at time of testing was 25 dB(A).

Acoustics - dB(A)@5mm

Acoustics - dB(A)@5mm

Western Digital's claim of a quiet drive is indeed backed up by our acoustic measurements, though it cannot claim to be the quietest. Its idle noise measurement of just over 30dB(A) makes it a few decibels louder than both the Hitachi 7K1000 and the Samsung T166 drives which we've recently tested in the AnandTech labs. The score does represent nearly a 3 decibel reduction from any Western Digital drive we've previously tested, however, and easily bests the Seagate 750GB 7200.10.

The drive's activity measurements of 38.7dB(A) show the same pattern. The drive is still roughly 4 decibels louder than the whisper-quiet SpinPoint T166, but shows up substantially better than most other desktop drives in this class. The noise emitted by the drive during periods of activity can best be described as a low "thumping" or "pulsing" noise that was not obtrusive but noticeable at times.

Thermals

Our thermal tests utilize sensor readings via the S.M.A.R.T. (Self-Monitoring, Analysis and Reporting Technology) capability of the drives and are reported by utilizing the Active SMART 2.42 utility. We also utilize thermal sensors and infrared measurement devices to verify our results. We test our drives in an enclosed case environment without the fans operational to simulate temperatures that could conceivably be reached in a near silent SFF or HTPC case design. We typically find the reported numbers drop anywhere from 18% to 25% with the case fans operational. Our base temperature level in the room at the time of testing was 25C.

Drive Operating Temperatures - Celsius

Drive Operating Temperatures - Celsius

At 37.2C idle, the WD7500AAKS ends up in the middle of the pack. The situation improves dramatically, however, when the drive is under heavy load, coming in at an impressive 46.2C. This score is currently bested only by the Samsung T166 and the WD7500AAKS's smaller sibling, the 500GB WD5000YS. Keep in mind that larger drives with more platters usually generate more heat, so the temperature result is all the more impressive.

HD Tune / HD Tach for your pleasure PCMark05 Performance
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  • miahallen - Wednesday, August 15, 2007 - link

    http://www.silentpcreview.com/forums/viewtopic.php...">Very good discussion concerning the problems with anandtech's sound measuring methodology here.
    quote:

    I really wasn't going to say anything here, but I feel compelled to do so. First, I almost completely disagree with nwavguy about the merits of close mic SPL measurement. The only good things about them are...

    1) you can use a poor SPL meter in an inadequate, noisy setting
    2) it's cheap

    The problems with Anandtech's methods are much greater than this, however. The HDDs are not even isloated from other noise sources which appear to be far louder than the HDDs being measured. That's totally illogical and careless if you're seeking any kind of accuracy in acoustical measurements.
    Reply
  • The Boston Dangler - Friday, August 10, 2007 - link

    for Samsung to offer larger drives Reply
  • Lord Evermore - Thursday, August 09, 2007 - link

    So...have all drives up to this point only had the drive shaft secured on one side? The end of the shaft just spinning in the air between the top platter and the casing? That seems like a very unlikely thing given how easily that could result in the platters moving and hitting the heads or even hitting the casing. Given the G forces they're rated to handle even when running makes it sound even less likely. Reply
  • Lord Evermore - Thursday, August 09, 2007 - link

    Oh, and haven't all drives had auto-parking heads for like a decade or more? The only reason the heads would move onto the platter during spin-up is if the controller specifically drives the armature to do so. So basically, SecurePark is WD saying "hey, we don't do something stupid with the heads anymore!"

    I hate how every company has to give their own trademarked name to a basic technology that everybody has.
    Reply
  • falc0ne - Thursday, August 09, 2007 - link

    I've noticed in stores 250, 320 and 400GB versions of AAKS are they the same revision drives? I'm ready to order one if so.
    Also, with the same capacities WD has drives in series KS.

    Please, I need support, I'm buying a new PC. Thank you
    Reply
  • Adul - Thursday, August 09, 2007 - link

    Where did you find the Seagate for 180? Reply
  • Gary Key - Thursday, August 09, 2007 - link

    At the time Dave wrote this, our price engine was showing ClubIT to have it for $188.89 if I remember right. I just checked and it was up to $199. We will get the article updated shortly. Reply
  • AdamK47 - Thursday, August 09, 2007 - link

    Want! Reply
  • gloinsir - Thursday, August 09, 2007 - link

    The following chart
    http://images.anandtech.com/graphs/wd750_080807108...">http://images.anandtech.com/graphs/wd750_080807108...
    , the Load Acoustics Chart, was missing results for the Hitachi 7K1000 with AAM/Off.
    Reply
  • Gary Key - Thursday, August 09, 2007 - link

    Fixed with a press of the refresh button... strange things today. Reply

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