[nzlug] Fans?!?

[cr]

On Wednesday 28 February 2007 21:15, Daniel Pittman wrote:
> cr <cr at orcon.net.nz> writes:
> > On Wednesday 28 February 2007 08:32, Vik Olliver wrote:
> >> On Wed, 2007-02-28 at 04:45 +1300, Nevyn wrote:
> >> > Unfortunately the fileserver is in my room, and a 12cm fan is just
> >> > way too noisy.
> >>
> >> There is the ultimate bodge: The use of a desk fan, fixed to a hole
> >> cut in the case with a chassis nibbler...
> >
> > Or, of course, you can (specially if it's a tower case) just leave the
> > side panels off completely, thus giving heaps of gentle flow-through
> > ventilation for your drives,
>
> Actually, watch out for that.  Many cases are designed to work correctly
> only if the side of the case, the drive bay covers and most of the PCI
> slot covers are present.
>
> Disrupting that airflow path can have significant effects; in the
> specific case you suggest the effect is normally to *reduce* airflow
> past the hard disks:
>
> Normal design has an intake at the front of the case, toward the bottom,
> where air is drawn in over the hard disks.  It then flows up past the
> GPU and CPU, then out exhaust fans in the power supply and
> (occasionally) on the back of the case.
>
> Without the side panel in place air can be drawn in through the open
> side of the case by the power supply fan, so you have less air motion
> past the CPU and GPU -- and practically none, only convection movement,
> over the hard disks.

The CPU, of course, has its own fan.   

I would have to say, though, that it's a matter of the individual hardware 
and case design - in my case (no pun intended!) the hard drives are nicely 
spaced out and seem to get more than adequate natural cooling as they're 
barely warm to the touch.   

There's also the motherboard chips and RAM to consider - on my current board 
the southbridge has a dinky little fan of its own, many don't.    But the 
airflow over  the board must be very much affected by the number of PCI cards 
installed and the IDE cables which (if most of the hard drive and CD slots 
are filled) form a big air dam at the back of the hard drive stack.   

> This can nicely cook your hardware for you.  My server case, for
> example, has close to fifteen degrees hard disk temperature difference
> between the case closed and open, purely due to airflow changes.
>
> Regards,
>         Daniel

I think it's very much a matter for individual consideration - the designers 
of a case can only guess at what configuration of boards and drives (and 
fans) are going to be put in it.

cr