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Date:      Wed, 10 Jul 2002 16:32:27 -0700
From:      Darren Pilgrim <dmp@pantherdragon.org>
To:        Terry Lambert <tlambert2@mindspring.com>
Cc:        a clever sheep <freebsd-chat@aard.org>, freebsd-chat@freebsd.org
Subject:   Re: 2u freebsd box and riser card drivers
Message-ID:  <3D2CC40B.AAB21291@pantherdragon.org>
References:  <20020710155003.GC500@malkavian.org> <3D2C9C2F.91398132@mindspring.com> <3D2C9E93.A8EBBD81@pantherdragon.org> <3D2CA2D6.E387A2D@mindspring.com>

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Terry Lambert wrote:
> 
> Darren Pilgrim wrote:
> > > They are just wires and connectors to extend the wires and connectors
> > > already there.  No drivers necessary.
> > >
> > > On a related note, I've been looking for a 1U case and riser that can
> > > handle 2 cards (one right-side-up, the other up-side-down), i.e. the
> > > cards go on opposite sides of the riser, with their connectors facing
> > > each other:
> >
> > Would the connectors being that close to each other impact signal
> > timing?
> 
> Does having adjacent connectors that close together on the motherboard
> impact signal timing?  8-).
> 
> If you don't like the idea on that basis, then I could live with
> right-hand riser to go with a seperately purchased left-hand riser;
> I can get a left-hand riser anywhere...

I didn't say I didn't like the idea, I just know that trace lengths
affect timing and that on a bus-type interface, timing is important.
Perhaps at 33/66MHz it doesn't really make a difference.

> I think the biggest issue will be that the card will end up facing
> chip-side-down rather than chip-side-up, as for most cards, so the
> heat disapation will be towards motherboard components that may
> also want to be disapating heat into the same small areas there,
> between-card-and-motherboard.
> 
> I think you can make the argument, though, that you will have that
> same problem with any card, even if it's right-side-up, because of
> it being parallel to the motherboard and the case top.

I would have thought that putting the cards chip-side down would allow
for simpler cooling as all the hot components would sit more or less in
the same air path.  In a thin, wide space like a 1U, more air along one
would probably be easier to do than adding seperate air paths.

> Now to find a motherboard that can handle 1G SIMMs, where the SIMM
> connector hardware is at a steeper angle than normal so that you
> can fit 4G in a 1U case... ;^).

You know, there's a point at which all this extra hardware will demand
a 2U case just so you can use larger fans. :) Or have you found a
company that will make small electric turbofans at a reasonable price?
I've seen 1-inch turbofans that pull no more juice than the average
80mm case fan and can move 170CFM when unobstructed and running at
nominal speed.  I just wouldn't want to put one in my desktop.

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