Where should the additional fan be placed in my PC for cooling?

Question

I have an additional 12V fan cooling the bottom part of my hard disk circuit board but I don't know if I am doing the right thing, because hard disk could get quite hot. Or should I place it to cool the motherboard or the ram? CPU and graphic card has its own fan.

I also realised that the top metal surface of the hard disk is used for emitting heat if I am not wrong? Should my fan cool it there instead?

I forgotten to state that I always leave my casing open. So I don't think there is any air ventilation problem. What I worry is will leaving the case open invites more dusts to settle on it? I am thinking of using a tissue paper to cover the graphic card to avoid dust because of its horizontal large surface. I doubt it will get short-circuit.

Answer 1

I always install two per case. You will get better air flow by balancing out the air pressure.
The one pulling in air creates a high pressure.
The one in the back puling out the air creates a low pressure. So together they are balanced.
Some people will tell you they only put a fan in the back. Those cases are the ones that dust builds up in and around the USB and CD openings.

Answer 2

I would use caution.
Adding an extra fan internally can sometimes hinder proper airflow as originally designed by the casing manufacturers.

Try to position the fan so that it enhances the existing airflow operation in the PC. If one fan is blowing air out have this new fan near the front enclosure blowing air in (for example).

It does not need to blow directly on the hard drive so long as the air near the drive has proper circulation.

regards,
Philip T

Answer 3

How much air flow do you have in your case?
If you have no way of venting the heat, you can put all the fans you want into your case, they simply won't help.
Place the fan wherever it can either force air in or out of the case itself, you need to create air movement through the case.

My machine uses 3 hard drive coolers, Zalman CPU and Video cooler fans and two 120 mm fans one for intake and one for output.

Answer 4

Per a test by Google,who has more hard drives, higher drive temperatures did not correspond to higher failure rates.

Per Google:
http://labs.google.com/papers/disk_failures.pdf
"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 them
by 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."

Answer 5

Use your system for about 45 minutes without the extra fan, then open it up (use a anti static wristband or ground yourself) and check which components are warmest.

Answer 6

well first of all on my rig, my PSU has a fan that helps cool the Mobo, and then I installed a PCI-slot fan. Keep everything cool, my graphics card has a fan on it also but that is never enough.