[Beowulf] Re: Airflow (Robert Fogt)

Jim Lux James.P.Lux at jpl.nasa.gov
Wed Jun 28 16:35:59 PDT 2006

At 11:40 AM 6/28/2006, David Mathog wrote:

> > How much harm does removing the computer case do?
>For airflow it's hard to generalize - it might be better or worse than
>the case which you removed.  Some cases do a great job of moving air
>where it needs to, and others just suck.

Almost always, airflow is worse without the case, but if there's a lot of 
airflow in the room, you may come out ahead.

>In terms of safety it doesn't seem like a very good idea.

Indeed.. the "oops, a paperclip just fell into the chassis and now it's 
sparking and smoking"  A typical PC power supply can put out 30-50 Amps 
plus at 5Volts... more than enough to start a fire.

>In terms of radio interference it is almost certainly in violation
>of dozens of U.S. statutes - unless maybe your whole machine room is

Not necessarily. The rules say you can't sell (distribute, market, etc.) 
something that isn't either exempt or has been tested to show 
compliance.  If you modify it yourself (e.g. by removing the covers) it's a 
bit more of a grey area.  You're responsible for not interfering with 
anyone else, but OTOH, you probably also aren't responsible for 
demonstrating compliance.

And, there's a sort of general de facto rule (or perhaps "guideline" in the 
"pirate code" sense) that if you radiate noise inside your own facility, 
but it's not detectable outside, then you're good to go.

This leaves aside interesting issues of RF safety, etc.

In any event, you're generally MUCH better off leaving the covers on. 

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