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Fan proximity to hard drive

Posted: Sun Apr 24, 2005 7:31 am
by neilgunton
I have mounted a new Samsung 160GB drive on the front bottom of the case, suspended on one of those elastic cord arrangements. As a result, the drive can no longer dispurse heat via the side connectors (since it is only touching the elastic). So, I tried putting an 80 mm Panaflow fan on top of the drive, attached with sticky velcro at the corners. This means there is a small gap (couple of mm) between the top of the drive and the fan in the spaces between the corner velcro.

A photo is here: http://www.neilgunton.com/public/photos/img_2504.jpg

Since the fan is facing upward, I am hoping that this means the air will be drawn across the surface of the top of the drive, through the gap and up. The fan is connected to a Fanmate controller, which will be used to slow the fan down to an almost inaudible level.

I am wondering a couple of things now:

1. Will this really help keep the drive cool? The machine is a Dell Precision, so there are no real vents on the front of the case. All I am doing is trying to move air around the drive and drive it (preferably) upward. Will the air movement through the small gap between the fan and the hard drive cover make much difference? I thought the small gap might somehow focus the air flow, while also making the whole thing more compact. I could put some kind of spacers in there, but then I thought the airflow would be more unfocused (i.e. perhaps not moving air over the actual drive so much).

2. Will the close proximity of a fan (i.e. electric motor, presumably with a corresponding magnetic field) to the hard drive have any bad affects? Even if the magnetic field effects are not large enough to actually change bits on the hard drive, could it slow the drive down perhaps (e.g. seek times)? Is such a magnetic field blocked at all by the metal of the hard drive case? The fan will be going fairly slow, so would this help matters?

I have thought about attaching a metal (probably aluminum) heatsink to the sides of the drive, but since I got the elastic suspension unit this is a little harder to do, because of way the elastic cords are. I could rig something up if people think it's worth it, but would it be? Do you think this fan arrangement useless, ok, adequate, or actually harmful?

Any insights appreciated...

Posted: Sun Apr 24, 2005 8:25 am
by Steve Rosenthal
Considering there are aftermarket drive coolers that put one or two fans in close proximity to the drive (albeit the underside), I'd assume the magnetic field issue is probably low-risk. However, judging from your pic, that's not much of an air-gap. I'd consider a front-to-back configuration to flow over the platters and the PCB. Those electronics can get hot too.

Just my thoughts.

--Steve

Posted: Sun Apr 24, 2005 9:58 am
by andywww
I agree with Steve, though since you've already got yours set up, you can see whether temps and noise are acceptable for you. I don't know about whether the magnetic field will slow the drive, but supposedly suspension will- someone posted a white paper about this a while back. The conclusion was that the effect was minor and generally unnoticeable though :).

Also, a comment about the size of the gap/fan placement. Having such a small gap means the fan must fight a lot of negative pressure, which tends to increase the noise of the fan as well as reduce CFM airflow.

A suggestion for how to mount the fan in a front to back blowing config: use doublesided foam tape in multiple layers as spacers with velcro attached to the top on the front of the case. This should be as easy to mount as attaching it directly to the HDD and should maximize use of the airflow provided by the fan, allowing you to reduce fan speed further.

Posted: Sun Apr 24, 2005 10:09 am
by Qwertyiopisme
The electromagnetic noise created b the fan wil not do anything negative at all (it's so weak and has such a low frequency). However I would flip the drive over and place the fan so it blows down with a larger gap, to get more airflow, and airflow over the pcb which is where the most heat sensitive bits are.

Posted: Sun Apr 24, 2005 5:14 pm
by neilgunton
Thanks for the advice... I think I will try the fan for a little bit as it is currently, since it would seem that it's not catastrophic (in terms of magnetic fields at least) to have a fan that close.

I'll try monitoring it and gauge how the fan and hard drive are doing together. Perhaps I'll try increasing the gap a little if it seems like the fan is working too hard (even at the very low rpm).

Thanks again, much appreciated!

-Neil