Posted by: tranquilpc | March 10, 2009

WD HDD temperatures (1)

The SQA-5H is fitted with standard WD GP HDDs

After special consideration, and 10 weeks of various test routines it was decided that the rotational speed  of the HDD cooling fan could be reduced from the standard 12V to a lower 6.9V – resulting in a quieter system.

With small changes to this 6.9V the HDD temperature would change in a non linear fashion.

There are various conditions which effect the HDD temperature – ie is the HDD spinning, and is it being read or wrote to  ?

WD GP drives are very smart, when idle they consume a miserly 2.5W (500GB) / 2.8W (1TB), when they are in standby (not spinning) the results are excellent both sizes are approx 0.4W.  During max read/write service they only consume 5.4W

During all tests carried out, with WD GP HDDs @ 6.9v (fan) @ 25’C (ambnt) – the monitored HDDs were always in specification (5-55’C) – typical / loaded results were 45-46’C.  Ie we can safely specify that amnt temp of 34’C is still within spec’n even if the HDDs are under load.  When a ‘normal’ stae is measured, ie the WHS has completed initial HDD balancing etc – the HDD temps generally will be in the low to mid 40’s

Further tests reveal, that if the voltage diode is removed, from the fan module (ie fan=12vdc – approx 30CFM), then the HDDs will run approx 7-8’C cooler- and therefore the system should support even fast / hot HDDs, should they be used.  But take note, below, cool HDDs, with frequent power on/off cycles can be subject to high failure modes, so it’s not ideal to ‘super cool’ the HDDs, without good cause (ie you are using 10,000 RPM drives).

Due to client feedback, and a substantial re-run of environmental tests -Tranquil now ships SQA / Ex / BBS2 systems with a 7.7V speed controlled fan – this extra voltage provides an increase of approx 9% more air flow, without any detectable acoustic increase, but bringing HDD temps down slightly, but not so much to cause ‘super cooled HDDs’.  The new fan modules are marked ‘C’ on the fan label.


Some clients, using high power (or even 10K) HDDs are choosing to replace the standard fan, with superior (fast but quiet) fans, ie the Panaflow, or the Papst 8412 NGME (57m3/h).  Any 80x80x25mm 12V DC fan can be fitted  to the SQA / Ex / BBS2 (as long as you can fit (solder) the wires to the power blades).


For further information on the WD GP drives – please check here.

An interesting read can also be found here  – it was carried out by Google (big user of HDDs) – and it’s interesting to read the summary pages… suggesting that ‘cool’ HDDs are actually more prone to failure than hot ones.  The most reliable HDD temperature, it would seem, based on a 4 year life cycle would be approx 35-40’C – HDDs with lower temperatures than this seem to be much more likely to fail, HDDs with temperature deltas of >45’C seem to be equally as reliable as those at 35’C (except for older disks).

“One of our key findings has been the lack of a consistent pattern of higher failure rates for higher temperature drives or for those drives at higher utilization levels. Such correlations have been repeatedly highlighted by previous studies, but we are unable to confirm themby observing our population. Although our data do not allow us to conclude that there is no such correlation, it provides strong evidence to suggest that other effects may be more prominent in affecting disk drive reliability in the context of a professionally managed data center deployment.”





Coming soon – the Panaflow fan – 21dbA @ 24CFM, best mix ?

Tranquil are now testing various speed control options / temperatures, using the latest Panaflow FBA08A12L – subject to the test results, existing SQA clients will be offered a free upgrade, and next generation SQA systems may be fitted with this fan module – details follow :

Panasonic’s FBA08A12L low speed 80mm fan features a hydro wave (fluid dynamic) bearing for the lowest possible levels of noise, vibration, and harmonics. The 12L Panaflo 80mm fans are the most sought after fans by PC enthusiasts. No other fan can match the Panaflo’s combination of real airflow and real noise ouput. While other fans may have similar numerical specifications, based on different measuring techniques. Most users have discovered that the Panaflo fan is quieter than similarly rated fans. At 24 CFM and 21dBA, this fan provides high airflow without excessive noise. An excellent choice for case cooling and for use as a case fan where low noise is required.

Noise: 21 dBA
Rotation Speed: 1900 RPM
Connectors (swappable): 2pin connector no adapter
Bearing Type: Hydro Wave
Current Draw: 0.1 A
Rated Voltage: 12 VDC



  1. Morten

    Current SQA customers can claim a new FAN module (fitted with the Panaflo fan). The new fan module has the same acoustic quality, but moves approx 2.5x more air, cooling the HDDs a little more.

    To claim, please send email to confirming the serial number on the back of the system, along with the original order number that you received when you ordered on-line.

    Your new fan module will be shipped within 48 hours. Once the module has been replaced, please return the original module to Tranquil PC Ltd.

  2. Thank you very much. Apreciate Tranquil’s great service to customers.


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