[rescue] Cooling dual SM81 SS20?

Skeezics Boondoggle skeezics at q7.com
Fri Jul 15 17:54:52 CDT 2005

On Fri, 15 Jul 2005, Michael-John Turner wrote:

> I've just installed a pair of SM81s (85 Mhz SuperSPARC-IIs) into an SS20
> and they seem to be working OK. One thing that concerns me a little is
> the heat - the CPUs get warm very quickly. Do I need extra cooling for
> them?  My PSU fans work fine and the machine probably won't have any
> other SBus cards in it, but I'm not sure if that's enough.

I've run lots of 20's with dual SM81s, but always in a cooled machine room
environment.  They definitely run hot in the pizzabox chassis (they do
much better in the SS1000/SC2000. :-)  I've always been partial to those 
CPUs; they are serious workhorses.

I've taken to adding external cooling to all my SS20s in regular desktop
settings.  In fact, the U1 CPU fan should actually fit in the narrow gap
between the SS20 motherboard and the cage, with a couple of tie wraps to
hold it in place - currently I tack them on the outside of the case, which
isn't pretty, but it's functional...  Fashion a power lead using the
unused floppy power connector, or a "Y" if necessary off the CD-ROM drive
power cable, and viola!  I've found that giving a little extra pull of air
across the Mbus/Sbus slots removes a LOT more heat than relying on the PS
fans alone, and I think my pizzabox SPARCs are a lot happier.

-- Chris

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