[Beowulf] A Cluster of Motherboard.

Alvin Oga alvin at Mail.Linux-Consulting.com
Fri Nov 11 00:22:24 EST 2005


hi ya

On Thu, 10 Nov 2005, Jim Lux wrote:

> Uhh.. thermal management for large systems can be a lot more complex than 
> just pushing bucketloads of air through.  Ask the folks designing blade 
> systems.

seems to be an ongoing issue .. but that is where all the fun is
to have the cpu running lower than other equivalent boxes
 
> >The cost of an aluminum plate and standoffs is trivial compared to a
> >case,

standoffs is about $0.01 - $0.02 each ... 
- you'll need say 4-6-9 of um for your motherboard ( a whole $0.10 :-)

but the purchasing dept that has to place that order for 10 standoffs
is gonna cost a mint, say 10-15 minutes of phone call time and chatting
about the in-laws so that the next time they call, they can also talk
person-to-person instead of voicemail and crossing ones fingers for a
return call

and we must not forget the $0.03 motherboard screws too :-)

> and once you have made one plate all the others can be readily
> >mass produced using a template and a hand drill.

alum plate is not much more expensive ... i hear numbers like $0.30/lb
of blank steel .. but you do have to buy it by the lb, say 4'x8' blanks
and have the "million dolar equipement" to cut and bend it into shape
 
> The material cost may be low, but you're not going to be out making 90 odd 
> aluminum plates with a hand drill (I assume you're talking an electric 
> drill, not an "eggbeater"), unless you're not very picky about tolerances 
> and fit.

some folks are more sophisticated ... using dremel ... or tools from
ace/orchard ...

> >I can fabricate a chassis for a mini itx cluster from aluminum plate and
> >aluminum angle stock with simple hand tools in about 2 days....

it should be about 5 minutes .. after finding the x-y coordinates
of the holes, assuming its just a flat metal and no cutouts
for the i/o brackets

> and I
> >could do it in hours if I owned a drill press and cutoff saw.
> >The main point is, it can be done cheaply and with simple tools.

unfortunately... its NOT that simple or realistic ...

and more importantly.. repeatable

> Yes, but if you pay yourself any sort of reasonable rate, it's not 
> necessarily cheaper, especially when you consider assembly time.

it 10x - 100x costs more in labor costs to:
	- find the store to sell the metal
	- find the purchasing folks to place the order
	- find the folks to get quotes
	- get the approval to place the order 
	- receive the parts
	- get the parts from shipping/receiveing onto your desk
	- .. endless list ..

	and since its not being shipped anywhere, we won't have to
	buy $2.oo cardboard boxes and $15 foam for shipping
	and all that handling and paperwork and christmas wrappings

> 2 days of hiring someone basically competent is probably about $500.

to get it done right ... it's more like $1,000/day ... and about 2-3 days
to get drawings that is usable by the machine shops 
	- cheaper labor will not always work better in the long run
	so we've decided to pay the good boyz the extra $$$ to get the
	stuff done right the first time .. and not worry about the
	1mon - 3mon delays due to screw ups with drawings by the 
	inexperienced "chassis" or sheet metal autocad'erz

	- anybody can draw lines and circles and bend here and bend there
	but it does NOT mean the machine shop can build it per drawing
	or that the system will work efficiently when it's on 24x7

	- say, 80% of the drawings are wrong and has to have followup
	phone calls to fix the drawings


fun stuff .. to get it done right ...

c ya
alvin

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