Hello all!

When a 160 GB Seagate 7200.7+ PATA was given to me as a gift, I started testing it in the mobile rack. The temperature according to Everest Home Edition was considerably hotter than a 120 GB Hitachi 7K250 PATA. This triggered a discussion over at StorageReview.

To make a long story short, my computer case (SuperPower Zephyr KS-201) is 4½ years old and by no means state of the art. It had the standard single case fan, front-intake, which was located at the bottom, blowing at nothing. An additional rear-exhaust fan was optional but there was only the standard fan in my KS-201. The temperatures below refer to two identical 120 GB Hitachi 7K250 PATA, #1 fixed and #2 in the mobile rack. The computer was started cold and measurements taken after 2-3 hours (temperatures stabilized) of very light load:

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When the Seagate substituted the Hitachi in the mobile rack, it was running at 48-49°C.

The discussion prompted me to move the fan from the front-intake position to the rear-exhaust position and the reduction in temperatures was amazing:

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When the Seagate substituted the Hitachi in the mobile rack, it was running at 37-38°C.

NDT (Net Drive Temperature = measured temperature - ambient temperature) has been lowered by 12°C for the Seagate compared to a 10°C reduction for the Hitachi. The fixed drive shows the least reduction in NDT, 7°C.

It seems like having a look inside your computer case is a good idea. If there only is a front-intake fan at the bottom, then it is probably only drawing dust into the case. Well, hopefully it is increasing general air circulation but not much more.

Moving the fan to the rear-exhaust position will draw fresh air through the front, cooling the drives. The CPU fan will also exhaust into this air flow and CPU/MB temperatures will also benefit, albeit to a lesser extent.

More modern computer cases have a standard rear-exhaust fan and an additional front-intake fan is optional. Some have both fans as standard. (The front-intake fan is located in front of the 3.5" drive bays to direct the air flow over the drives.) This makes it less of an issue in more recent computer cases.

I wonder ...... ??? ...... what the designer of the KS-201 was thinking. Why not ship it with a standard rear-exhaust fan and an additional front-intake fan as an option. (I actually believe that fans in both positions would make the situation worse for the drives, compared to a single rear-exhaust fan.)

Christer

Hi NightOwl!

I use Everest Home Edition which is a 'slimmed' freeware version. To the best of my knowledge, it is accurate and gets the data from the S.M.A.R.T.

The probe that supplies the data from the HDD is located internally, close to the actuator arms (or whatever they are called).

The probe for the MB and CPU is probably on-chip but some utilize a probe between the CPU and the heat sink.

The ideal situation is to have a line of air flow from the front (inlet) to the rear (exhaust). The fan in the power supply is what cheaper cases rely on for exhaust but for higher performance computers, it is not enough.

If a fan is fitted to the side panel, directed onto the CPU, it should be ducted. Otherwise the two air flows will interact and produce more turbulence than cooling. In my case, the improved air flow reduced the Net Temperature of the MB and CPU by 3°C and the HDDs by 8°C (average).

I just moved the fan but even if you have to buy a new fan it is a purchase with a high cost/benefit ratio.

Christer

Yes, there are different types of coolers but getting an 8°C reduction in NDT for free is a good starting point.

It is possible that my computer case is the 'worst scenario' and I am still wondering what the designer was thinking. Were any tests carried out with different fan positions? I don't think so!

Christer

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It's been difficult to avoid that when writing posts to the discussions.

Anyway, in my case the air flow is better inside the case ...... ...... but it may be different in other cases!

Christer

Christer wrote on Nov 17^th, 2005 at 3:29am:

I like my computers to be silent, so I have spent lots of time trying to get the most cooling out of the fewest noisemakers.

Air flow inside a computer case vaires based on the case, the fan, and what you have inside the case.  In my cases, having the fan at the bottom creates a positive presure in the case, which helps keep dust from entering your computer through cracks around your CD and floppy drives.  Dust in those drives can be a killer, as my friend learned through experience.

Usually, the power supply is at the top of the case, and it will exhaust air out the back-top of the case, creating a natural flow.  The front fan brings cool air in, the hot air rises, the powersupply sends it out.

Every fan has different charastics.  Some move more air at a lower RPM but can't produce as much presure.  If a fan can't produce enough static presure to continue moving air into the case, that is when it becomes benificial to move it to the exhaust position.  The fan can easily pull hot air out of the case, and cooler air moves in to take its place.

As far as hard drives go, I learned the hard way that heat kills a drive faster than anything.  Most cases come with no consideration for hard drive cooling.  

I try to put my drives in the lower-front of the case, where the incoming cool air flows over it, and that seems sufficent.  I agree with Rad that any airflow at all makes a big difference.

Readers of this thread who are interested in monitoring the temperature of hard disk drives (and optionally controlling the fan speed) will be interested in the SpeedFan tool discussed in the thread Monitor Hard Disk Temperature.

SIW is another application with the corresponding functions compared to Everest but for my Hitachi, it produces gibberish for temperature:


It seems to be "hit or miss" but I don't know why.

Christer