[Wiltshire] Computer hardware - case fans

[David Fletcher]

On Tuesday 27 Oct 2009, Greg Browne wrote:
> I have one, so they must be readily available, but mine came from a computer
> fair.
> 
> However, I would think carefully before doing such a thing, as you need to
> think through the air flow paths quite carefully. The danger is as follows,
> for a standard case. (Yours, of course, might not be a standard case and you
> might be already aware of this problem)
No, it's not a standard case. I designed and built it myself.

> 
> Instead of creating a low pressure area at the rear of the case that draws a
> through flow of air, in through the front and side of the case, you will
> create a short circulating area of air flow, in through the rear and out
> through the rear mounted power supply. This in turn can create an area of
> stagnant air, further forward, just where the hard drive is likely to be
> mounted. I have seen people do this (mistakenly mounting an extra case fan
> the wrong way around) with the result that hard drives fail within months
> from overheating.
I'm thinking about re-building the machine with one of these:-
http://www.intel.com/products/desktop/motherboards/D945GSEJT/D945GSEJT-overview.htm

with the fan next to the board's I/O mask plate and an IEC power inlet socket 
next to the fan, feeding an open frame 12V DC switcher i.e. there will be no 
other fan.

The fan will send a current of air towards the front of the case, via the 12V 
switcher. The hard drive is at the front with the vent holes underneath, so 
that should also receive some air. I also think a deflector plate to try to 
send some of the air stream sideways over the motherboard heat sinks would be 
good.

All this will involve a bit of redesign and a trip to Metalfast for a fresh 
chunk of aluminium to fabricate a revised back plate for the case.

At present there's the smallest ATX power supply I could buy with, of course, 
its own cooling fan venting out of the back of the case. Experience has 
demonstrated that sucking air out of the back does not create the flow I 
need, so yes there appears to be an area of stagnant air over the motherboard 
in general which is why I've had to add a couple of small fans to cool what 
is supposed to be a fanless board.