[Sussex] Hardware Help

[Steve Dobson]

Colin

On Fri, May 13, 2005 at 10:18:59AM +0100, Colin Tuckley wrote:
> Steve Dobson wrote:
> > The CPU has a fan (35mm dia) on top of the cooling veins. While it is
> > very close to the top of the 1U rack-mount case (no more than 2mm) there
> > is a vent in the case lid which will all the fan to vent.  The rack-mount
> > case has a cooling duct two 35mm fans that vent to the rear of the
> > rack-mount, but one of the fans is next to the CPU cooling veins and would
> > be drawing air across the cooling surface.
> 
> I think you will find you have the CPU fan airflow direction reversed. They
> normally suck air in from the top and force it down into the heatsink fins
> and then out the sides.

Yep - for both fan sets.
 
> >   1). Remove the cooling duct
> 
> Not a good idea

I can see that now the fans are blowing.
 
> >   2). Cut two holes in the cooling duct to run the power wires.
> 
> If you make the holes small enough and fit grommets or otherwise protect the
> wires from the metal edges this should be good. How much will the wires
> restrict the airflow in the duct?

They should take up more than 20-25% of the surface area of the fans.
Of course they won't be up against them so they shouldn't be a problem.
 
> >       This will result in one fan drawing air from
> >       the top of the CPU cooling veins and other trying to draw
> >       air from the left to the right.
> 
> Not if my thoughts on Heatsink airflow direction are correct

Which is was.
 
> >   3). Remove the CPU fan (no not to have the odd airflow) and just
> >       rely on the fan in the duct
> 
> A very BAD idea.

Agreed.  Looks like it is option 2 then.

Ta for your help
Steve