[Beowulf] /. Cooler room or cooler servers?

Jim Lux James.P.Lux at jpl.nasa.gov
Fri Apr 8 09:35:52 PDT 2005

At 07:47 AM 4/8/2005, Joshua Halpern wrote:
>Jim Lux wrote:
>>At 04:27 PM 4/7/2005, Mark Hahn wrote:
>>This what I would imagine off hand...  Comparable computational power of 
>>a given IC fabrication technology (feature size/voltage/etc) will 
>>dissipate similar amounts of power. And this is what you said you measured.
>Shifting away from silicon to large bandgap semiconductors could be a way 
>out.  In principle such devices could operate at much higher 
>temperatures.  The development push is coming from operation in hostile 
>environments, such as car engines and stand alone operations where cooling 
>is not available.

And in space.. Higher operating temperatures are very good, because you 
have to get rid of heat by rejecting it with a radiator to cold 
space.  Moving the temperature of the radiator up from 300K to 400K helps a 
whole bunch (that T^4).. you can make the radiator 1/3 the size.

>At this point I would guess that the best material would be silicon 
>carbide rather than  gallium nitride.  This is all pie in the sky right 
>now but there are no first principle obstacles just money and time.

Well... there are a few yield problems, and so far, many hundreds of 
millions (if not billions) of dollars have been spent on trying to improve 
it without huge success.  Don't expect to be seeing 0.25 micron linewidth 
12" wafers of SiC coming off the line anytime soon.  The big use of SiC now 
is White LEDs, I think.

>Joshua Halpern

James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875

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